Publications by authors named "Jianqi Zhang"

99 Publications

High Miscibility Compatible with Ordered Molecular Packing Enables an Excellent Efficiency of 16.2% in All-small-molecule Organic Solar Cells.

Adv Mater 2021 Nov 13:e2106316. Epub 2021 Nov 13.

CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China.

In all-small-molecule organic solar cells (ASM-OSCs), a high short circuit current (J ) usually needs a small phase separation, while a high fill factor (FF) is generally realized in a highly ordered packing system. However, small domain and ordered packing always contracted each other in ASM-OSCs, leading to a mutually restricted J and FF. In this study, we propose alleviating the previous dilemma by the strategy of obtaining simultaneous good miscibility and ordered packing through modulating homo- and hetero- molecular interaction. By moving the alkyl-thiolation side chains from para- to meta-position in the small-molecule donor, the surface tension and molecular planarity are synchronously enhanced, resulting in compatible properties of good miscibility with acceptor BTP-eC9 and strong self-assemble ability. As a result, an optimized morphology with multi-length scale domains and highly ordered packing is realized. The device exhibits a long carrier lifetime (39.8 us) and fast charge collection (15.5 ns). A record efficiency of 16.2% with a high FF of 75.6% and a J of 25.4 mA cm in the ASM-OSCs is obtained. These results demonstrate that the strategy of simultaneously obtaining good miscibility with high crystallinity could be an efficient photovoltaic material design principle for high performance ASM-OSCs. This article is protected by copyright. All rights reserved.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adma.202106316DOI Listing
November 2021

Electron-deficient TVT unit-based D-A polymer donor for high-efficiency thick-film OSCs.

Nanotechnology 2021 Nov 15;33(6). Epub 2021 Nov 15.

CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, People's Republic of China.

As the power conversion efficiencies of organic solar cells (OSCs) have been improved continuously in recent years, more attention will be paid to the industrial production and practical application of OSCs. However, there are still many problems to be solved in the process of large-scale production. Among them, reducing the costs of the materials and enhancing the film-thickness tolerance of the active layer are the two key points. Therefore, it is urgent to develop organic semiconductor materials which are easy to synthesize and suitable for the construction of high-efficiency, thick-film OSCs. In this work, we have focused on the (E)-2-[2-(thiophen-2-yl)vinyl]thiophene (TVT) unit because of its unique coplanar structure. And we noticed that TVT was mostly used as an electron-donating unit in the previous reports. However, we have modified TVT into electron-withdrawing unit by the introduction of fluorine atoms/ester groups. And two new donor-acceptor (D-A) copolymers have been obtained by combining the electron-withdrawing TVT unit with benzo[2,1-b:4,5-b']dithiophene (BDT) unit. Among them, the polymer based on the ester modified TVT unit presents excellent photovoltaic performance by virtue of its good solubility and preferable molecular stacking mode, and the corresponding devices also show extraordinarily high-thickness tolerance. The emergence of this new electron-withdrawing TVT unit will undoubtedly further promote the development of low-cost, high-efficiency, thick-film OSCs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1361-6528/ac335aDOI Listing
November 2021

A Universal Nonhalogenated Polymer Donor for High-Performance Organic Photovoltaic Cells.

Adv Mater 2021 Oct 13:e2105803. Epub 2021 Oct 13.

State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.

Nonhalogenated polymers have great potential in the commercialization of organic photovoltaic (OPV) cells due to their advantage in low-cost preparation. However, non-halogenated polymers usually have high highest occupied molecular orbital (HOMO) energy levels and inferior self-aggregation properties in solution, thus resulting in low power conversion efficiencies (PCEs). Herein, two nonhalogenated polymers, PB1 and PB2, are prepared. When the polymers are used to fabricate OPV cells with BTP-eC9, the PB1-based device only gives a PCE of 5.3%, while the PB2-based device shows an outstanding PCE of 17.7%. After the introduction of PBDB-TF as the third component, the PB2:PBDB-TF:BTP-eC9-based device with an optimal weight ratio of 0.5:0.5:1 achieves a PCE up to 18.4%. More importantly, PB2 exhibits good compatibility with various nonfullerene acceptors to achieve better PCEs than those of classical polymer (PBDB-T and PBDB-TF)-based devices. When PB2 is combined with a wide-bandgap electron acceptor (F-BTA3), this device shows excellent PCE of 27.1% and 24.6% for 1 and 10 cm devices, respectively, under light intensity of 1000 lux light-emitting diode illumination. These results provide new insight in the rational design of novel nonhalogenated polymer donors for further development of low-cost materials and broadening the application of OPV cells.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adma.202105803DOI Listing
October 2021

A Bioinspired Adhesive-Integrated-Agent Strategy for Constructing Robust Gas-Sensing Arrays.

Adv Mater 2021 Oct 10:e2106067. Epub 2021 Oct 10.

CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, CAS Center for Excellence in Nanoscience, Key Laboratory of Photochemical Conversion and Optoelectronic Materials & CAS-HKU Joint Laboratory on New Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.

Gas sensors based on organic molecules are attractive for their tailored molecular structures and controllable functions, but weak interfacial adhesion between sensing materials and supporting substrates has severely hampered their practical applications, particularly in harsh environments. Here, inspired by the combined anchoring-recognizing feature of natural olfactory systems, an adhesive-integrated-agent strategy to integrate the adhesive unit (poly(dimethylsiloxane)) with the sensing unit (organoplatinum(II)) into one chemistry entity, creating robust and sensitive nanobelt array gas sensors is demonstrated. Systematic theoretical and experimental studies reveal that incorporating adhesive units significantly enhances the interfacial adhesion of the array sensors and gas-bridged super-exchange electronic couplings of sensing units ensure their efficient gas-sensing performance. The high shear strength of ≈7.05 × 10 N m allows these arrays to resist aggressive ultrasonication, tape peeling, or repeated bending without compromising their sensing performance. This molecular engineering strategy opens a new guideline to develop robust gas sensors.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adma.202106067DOI Listing
October 2021

Single-Junction Organic Photovoltaic Cell with 19% Efficiency.

Adv Mater 2021 Oct 31;33(41):e2102420. Epub 2021 Aug 31.

State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, China.

Improving power conversion efficiency (PCE) is important for broadening the applications of organic photovoltaic (OPV) cells. Here, a maximum PCE of 19.0% (certified value of 18.7%) is achieved in single-junction OPV cells by combining material design with a ternary blending strategy. An active layer comprising a new wide-bandgap polymer donor named PBQx-TF and a new low-bandgap non-fullerene acceptor (NFA) named eC9-2Cl is rationally designed. With optimized light utilization, the resulting binary cell exhibits a good PCE of 17.7%. An NFA F-BTA3 is then added to the active layer as a third component to simultaneously improve the photovoltaic parameters. The improved light unitization, cascaded energy level alignment, and enhanced intermolecular packing result in open-circuit voltage of 0.879 V, short-circuit current density of 26.7 mA cm , and fill factor of 0.809. This study demonstrates that further improvement of PCEs of high-performance OPV cells requires fine tuning of the electronic structures and morphologies of the active layers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adma.202102420DOI Listing
October 2021

Completely non-fused electron acceptor with 3D-interpenetrated crystalline structure enables efficient and stable organic solar cell.

Nat Commun 2021 Aug 24;12(1):5093. Epub 2021 Aug 24.

State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular, Sciences CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry Chinese Academy of Sciences, Beijing, People's Republic of China.

Non-fullerene acceptors (NFAs) based on non-fused conjugated structures have more potential to realize low-cost organic photovoltaic (OPV) cells. However, their power conversion efficiencies (PCEs) are much lower than those of the fused-ring NFAs. Herein, a new bithiophene-based non-fused core (TT-Pi) featuring good planarity as well as large steric hindrance was designed, based on which a completely non-fused NFA, A4T-16, was developed. The single-crystal result of A4T-16 reveals that a three-dimensional interpenetrating network can be formed due to the compact π-π stacking between the adjacent end-capping groups. A high PCE of 15.2% is achieved based on PBDB-TF:A4T-16, which is the highest value for the cells based on the non-fused NFAs. Notably, the device retains ~84% of its initial PCE after 1300 h under the simulated AM 1.5 G illumination (100 mW cm). Overall, this work provides insight into molecule design of the non-fused NFAs from the aspect of molecular geometry control.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-021-25394-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8384863PMC
August 2021

Hydrophilicity gradient in covalent organic frameworks for membrane distillation.

Nat Mater 2021 Nov 22;20(11):1551-1558. Epub 2021 Jul 22.

Frontiers Science Center for High Energy Material, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, P. R. China.

Desalination can help to alleviate the fresh-water crisis facing the world. Thermally driven membrane distillation is a promising way to purify water from a variety of saline and polluted sources by utilizing low-grade heat. However, membrane distillation membranes suffer from limited permeance and wetting owing to the lack of precise structural control. Here, we report a strategy to fabricate membrane distillation membranes composed of vertically aligned channels with a hydrophilicity gradient by engineering defects in covalent organic framework films by the removal of imine bonds. Such functional variation in individual channels enables a selective water transport pathway and a precise liquid-vapour phase change interface. In addition to having anti-fouling and anti-wetting capability, the covalent organic framework membrane on a supporting layer shows a flux of 600 l m h with 85 °C feed at 16 kPa absolute pressure, which is nearly triple that of the state-of-the-art membrane distillation membrane for desalination. Our results may promote the development of gradient membranes for molecular sieving.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41563-021-01052-wDOI Listing
November 2021

Efficient N- and O-Sensing Properties of PtSe With Proper Intrinsic Defects.

Front Chem 2021 24;9:676438. Epub 2021 May 24.

School of Physics and Optoelectronic Engineering, Xidian University, Xi'an, China.

Developing efficient N and O gas sensors is of great importance to our daily life and industrial technology. In this work, first-principles calculations are performed to study the N and O gas-sensing properties of pure and defected PtSe. It is found that both N and O adsorb weakly on pure PtSe, and adsorption of the molecules induces negligible changes in the electrical and optical properties. Whereas the [email protected] anti-site defect significantly improves the N adsorption capacity of PtSe and induces notable changes in the electrical property. Similar results are also observed for the Pt and Se vacancies and [email protected] anti-site defects when examining O adsorption. In addition, notable changes in the optical absorption spectra of the PtSe with [email protected] defect are induced upon N adsorption, which also occurs for PtSe with Pt and Se vacancies and [email protected] anti-site defects upon O adsorption. These results demonstrate that PtSe with the corresponding defects can be both excellent electrical and optical sensors for detecting N and O gases. Our work offers a new avenue for preparing efficient gas sensors.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fchem.2021.676438DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8181151PMC
May 2021

Side-Chain Engineering for Enhancing the Molecular Rigidity and Photovoltaic Performance of Noncovalently Fused-Ring Electron Acceptors.

Angew Chem Int Ed Engl 2021 Aug 30;60(32):17720-17725. Epub 2021 Jun 30.

College of Materials Science and Opto-Electronic Technology &, Center of Materials Science and Optoelectronics Engineering &, CAS Center for Excellence in Topological Quantum Computation &, CAS Key Laboratory of Vacuum Physics, University of Chinese Academy of Sciences, Beijing, 100049, China.

Side-chain engineering is an effective strategy to regulate the solubility and packing behavior of organic materials. Recently, a unique strategy, so-called terminal side-chain (T-SC) engineering, has attracted much attention in the field of organic solar cells (OSCs), but there is a lack of deep understanding of the mechanism. Herein, a new noncovalently fused-ring electron acceptor (NFREA) containing two T-SCs (NoCA-5) was designed and synthesized. Introduction of T-SCs can enhance molecular rigidity and intermolecular π-π stacking, which is confirmed by the smaller Stokes shift value, lower reorganization free energy, and shorter π-π stacking distance in comparison to NoCA-1. Hence, the NoCA-5-based device exhibits a record power conversion efficiency (PCE) of 14.82 % in labs and a certified PCE of 14.5 %, resulting from a high electron mobility, a short charge-extraction time, a small Urbach energy (E ), and a favorable phase separation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.202106753DOI Listing
August 2021

Efficient Charge Transport Enables High Efficiency in Dilute Donor Organic Solar Cells.

J Phys Chem Lett 2021 May 21;12(20):5039-5044. Epub 2021 May 21.

Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping 58183, Sweden.

The donor/acceptor weight ratio is crucial for photovoltaic performance of organic solar cells (OSCs). Here, we systematically investigate the photovoltaic behaviors of PM6:Y6 solar cells with different stoichiometries. It is found that the photovoltaic performance is tolerant to PM6 contents ranging from 10 to 60 wt %. Especially an impressive efficiency over 10% has been achieved in dilute donor solar cells with 10 wt % PM6 enabled by efficient charge generation, electron/hole transport, slow charge recombination, and field-insensitive extraction. This raises the question about the origin of efficient hole transport in such dilute donor structure. By investigating hole mobilities of PM6 diluted in Y6 and insulators, we find that effective hole transport pathway is mainly through PM6 phase in PM6:Y6 blends despite with low PM6 content. The results indicate that a low fraction of polymer donors combines with near-infrared nonfullerene acceptors could achieve high photovoltaic performance, which might be a candidate for semitransparent windows.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jpclett.1c01219DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8280696PMC
May 2021

Electrical Loss Management by Molecularly Manipulating Dopant-free Poly(3-hexylthiophene) towards 16.93 % CsPbI Br Solar Cells.

Angew Chem Int Ed Engl 2021 Jul 21;60(30):16388-16393. Epub 2021 Jun 21.

Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.

Inorganic cesium lead halide perovskites offer a pathway towards thermally stable photovoltaics. However, moisture-induced phase degradation restricts the application of hole transport layers (HTLs) with hygroscopic dopants. Dopant-free HTLs fail to realize efficient photovoltaics due to severe electrical loss. Herein, we developed an electrical loss management strategy by manipulating poly(3-hexylthiophene) with a small molecule, i.e., SMe-TATPyr. The developed P3HT/SMe-TATPyr HTL shows a three-time increase of carrier mobility owing to breaking the long-range ordering of "edge-on" P3HT and inducing the formation of "face-on" clusters, over 50 % decrease of the perovskite surface defect density, and a reduced voltage loss at the perovskite/HTL interface because of favorable energy level alignment. The CsPbI Br perovskite solar cell demonstrates a record-high efficiency of 16.93 % for dopant-free HTL, and superior moisture and thermal stability by maintaining 96 % efficiency at low-humidity condition (10-25 % R. H.) for 1500 hours and over 95 % efficiency after annealing at 85 °C for 1000 hours.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.202105176DOI Listing
July 2021

Achieving a Higher Energy Charge-Transfer State and Reduced Voltage Loss for Organic Solar Cells using Nonfullerene Acceptors with Norbornenyl-Functionalized Terminal Groups.

ACS Appl Mater Interfaces 2021 Jun 18;13(21):24765-24773. Epub 2021 May 18.

Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.

Achieving a high-energy charge-transfer state () and concurrently reduced energy loss is of vital importance in boosting the open-circuit voltage () of organic solar cells (OSCs), but it is difficult to realize. We report herein a novel design tactic to achieve this goal by incorporating a three-dimensional (3D) shape-persistent norbornenyl group into the terminals of acceptor-donor-acceptor-type nonfullerene acceptors (NFAs). Compared with ITIC-based OSCs, norbornenyl-fused 1,1-dicyanomethylene-3-indanone (CBIC) terminals endow -based OSCs with simultaneously higher and lower radiative and non-radiative voltage loss, hence enhancing by 90 mV. CBIC also improves the miscibility and modulates the molecular packing structures for efficient charge carrier transport and a better short-circuit current density in -based OSCs. Consequently, the power conversion efficiency is improved by 22%, compared to that of the OSC based on ITIC. Furthermore, the effectiveness of the use of CBIC as the terminals is observed using different electron-donating cores. The utilization of the 3D shape-persistent building blocks represents a breakthrough in the design strategies for terminal groups toward efficient NFA-based OSCs with high .
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.1c03840DOI Listing
June 2021

π-Extended Nonfullerene Acceptors for Efficient Organic Solar Cells with a High Open-Circuit Voltage of 0.94 V and a Low Energy Loss of 0.49 eV.

ACS Appl Mater Interfaces 2021 May 6;13(19):22531-22539. Epub 2021 May 6.

Chinese Academy of Sciences (CAS) Key Laboratory of Nano System and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China.

A combination of high open-circuit voltage () and short-circuit current density () typically creates effective organic solar cells (OSCs). Y5, a member of the Y-series acceptors, can achieve high of 0.94 V with PM6 but low of 12.8 mA cm. To maintain the high while increasing the of devices, we developed a new nonfullerene acceptor, namely, BTP-C2C4-N, by extending the conjugation of a Y5 molecule with a naphthalene-based end acceptor. In comparison with Y5-based devices, PM6:BTP-C2C4-N-based devices exhibited significantly higher of 18.2 mA cm followed by a high . To further increase the photovoltaic properties of BTP-C2C4-N analogues, BTP-C4C6-N and BTP-C6C8-N molecules with better processability and film morphology are obtained by adjusting the alkyl branched chain length. The optimized OSCs based on BTP-C4C6-N with a moderate alkyl branched chain length exhibited the best PCE of 12.4% with a high of 0.94 V and of 20.7 mA cm. Notably, the devices achieved a low energy loss of 0.49 eV (0.51 eV for Y5 system) accompanied by a small nonradiative energy loss. The results indicate that nonfullerene acceptors with extended terminal motifs and optimized branched chain lengths can effectively enhance the performance of OSCs and reduce energy loss.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.1c04273DOI Listing
May 2021

Small Exciton Binding Energies Enabling Direct Charge Photogeneration Towards Low-Driving-Force Organic Solar Cells.

Angew Chem Int Ed Engl 2021 Jul 8;60(28):15348-15353. Epub 2021 Jun 8.

CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China.

Organic solar cells (OSCs) with nonfullerene acceptors (NFAs) exhibit efficient charge generation under small interfacial energy offsets, leading to over 18 % efficiency for the single-junction devices based on the state-of-the-art NFA of Y6. Herein, to reveal the underlying charge generation mechanisms, we have investigated the exciton binding energy (E ) in Y6 by a joint theoretical and experimental study. The results show that owing to strong charge polarization effects, Y6 has remarkable small E of -0.11-0.15 eV, which is even lower than perovskites in many cases. Moreover, it is peculiar that the photoluminescence is enhanced with temperature, and the energy barrier for separating excitons into charges is evidently lower than the thermal energy according to the temperature dependence of photoluminescence, manifesting direct photogeneration of charge carriers enabled by weak E in Y6. Thus, charge generation in NFA-based OSCs shows little dependence on interfacial driving forces.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.202105156DOI Listing
July 2021

A New Conjugated Polymer that Enables the Integration of Photovoltaic and Light-Emitting Functions in One Device.

Adv Mater 2021 Jun 25;33(22):e2101090. Epub 2021 Apr 25.

Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.

Exploring the intriguing bifunctional nature of organic semiconductors and investigating the feasibility of fabricating bifunctional devices are of great significance in realizing various applications with one device. Here, the design of a new wide-bandgap polymer named PBQx-TCl (optical bandgap of 2.05 eV) is reported, and its applications in photovoltaic and light-emitting devices are studied. By fabricating devices with nonfullerene acceptors BTA3 and BTP-eC9, it is shown that the devices exhibit a high power conversion efficiency (PCE) of 18.0% under air mass 1.5G illumination conditions and an outstanding PCE of 28.5% for a 1 cm device and 26.0% for a 10 cm device under illumination from a 1000 lux light-emitting diode. In addition, the PBQx-TCl:BTA3-based device also demonstrates a moderate organic light-emitting diode performance with an electroluminescence external quantum efficiency approaching 0.2% and a broad emission range of 630-1000 nm. These results suggest that the polymer PBQx-TCl-based devices exhibit outstanding photovoltaic performance and potential light-emitting functions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adma.202101090DOI Listing
June 2021

An Efficiency of 16.46% and a Lifetime of Over 4000 h for the PM6:Y6 Inverted Organic Solar Cells Enabled by Surface Acid Treatment of the Zinc Oxide Electron Transporting Layer.

ACS Appl Mater Interfaces 2021 Apr 13;13(15):17869-17881. Epub 2021 Apr 13.

School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei 230027, P. R. China.

For the inverted organic solar cells (OSCs), the interface contacts between the ZnO electron transporting layer and the organic active layer play an important role in the device performance and stability. Since the solution-processed ZnO surface always contains some base or zinc salt contaminants, we explored how the surface pH conditions influence the performance and stability of the nonfullerene acceptor (NFA) cells. A tight relationship between the surface pH condition and the device performance and stability was established. Specifically, device performance and stability were improved by treating the ZnO films with acid solutions but worsened after base treatment. The large number of hydroxyl groups on the surface of the solution-processed ZnO films was proved to be the main reason for the surface pH condition-related performance, which caused oxygen-deficient defects and unfavorable vertical phase separation in the blend films, hindered the photogenerated charge transfer and collection, and consequently resulted in low short-circuit current density and power conversion efficiency (PCE). The surface -OH groups also boosted the photocatalytic activity and led to fast degradation of the nonfullerene acceptor. Removal of the surface -OH groups can alleviate such problems. Different acid solutions, ZrAcac, 2-phenylethylmercaptan (PET), and glutamic acid (GC), were used to treat the ZnO films, and PET treatment was the most effective treatment for performance improvement. An efficiency of 16.46% was achieved for the PM6:Y6 cells and the long-term stability under continuous illumination conditions was significantly improved with a lifetime of over 4000 h (4410 h), showing the excellent long-term stability of this heterojunction solar cell. Our understanding of the surface pH condition-related device performance and stability would guide the development of a feasible method for solving the interface problems in OSCs. We also provide a practical strategy to modify ZnO with acid solutions for high-performance and stable NFA OSCs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.1c02613DOI Listing
April 2021

Metallated Graphynes as a New Class of Photofunctional 2D Organometallic Nanosheets.

Angew Chem Int Ed Engl 2021 May 7;60(20):11326-11334. Epub 2021 Apr 7.

Department of Applied Biology and Chemical Technology and Research Institute for Smart Energy, The Hong Kong Polytechnic University (PolyU), Hung Hom, Hong Kong, P. R. China.

Two-dimensional (2D) nanomaterials are attracting much attention due to their excellent electronic and optical properties. Here, we report the first experimental preparation of two free-standing mercurated graphyne nanosheets via the interface-assisted bottom-up method, which integrates both the advantages of metal center and graphyne. The continuous large-area nanosheets derived from the chemical growth show the layered molecular structural arrangement, controllable thickness and enhanced π-conjugation, which result in their stable and outstanding broadband nonlinear saturable absorption (SA) properties (at both 532 and 1064 nm). The passively Q-switched (PQS) performances of these two nanosheets as the saturable absorbers are comparable to or higher than those of the state-of-the-art 2D nanomaterials (such as graphene, black phosphorus, MoS , γ-graphyne, etc.). Our results illustrate that the two metallated graphynes could act not only as a new class of 2D carbon-rich materials, but also as inexpensive and easily available optoelectronic materials for device fabrication.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.202014835DOI Listing
May 2021

An Optical Fiber Sensor Coated with Electrospinning Polyvinyl Alcohol/Carbon Nanotubes Composite Film.

Sensors (Basel) 2020 Dec 7;20(23). Epub 2020 Dec 7.

School of Physics and Optoelectronic Engineering, Xidian University, Xi'an 710071, China.

A fiber-optics tapered sensor that is covered by an electrospinning polyvinyl alcohol (PVA) nanofiber film, is demonstrated to measure humidity and temperature simultaneously. A section multi-mode fiber (MMF) was sandwiched between two leading-in and out single mode fibers (SMFs), which was further tapered down to 29 μm to promote the humidity sensitivity of the sensor. A thin layer of electrospinning PVA nanofiber film was uniformly coated on the MMF taper region by electrospinning technology. In order to promote the humidity sensitivity and mechanical strength of electrospinning nanofibers, the carbon nanotubes (CNTs) were mixed into PVA to formed PVA/CNTs composite nanofiber film. A Fiber Bragg Grating (FBG) was cascaded with the humidity sensing fiber to monitor the ambient temperature simultaneously. The addition of CNTs effectively eliminated the cracks on the electrospinning nanofiber and made it more uniform and smoother. As experimental results show, the humidity sensitivity of the sensor with PVA/CNTs film was 0.0484 dB/%RH, an improvement of 31.16% compared to that of the sensor with PVA film, for which sensitivity is 0.0369 dB/%RH. The nanofiber humidity-sensitive film constructed using electrospinning had a satisfactory humidity response, special 3D structure and extensive application prospect.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/s20236996DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7731010PMC
December 2020

Synergistic Optimization Enables Large-Area Flexible Organic Solar Cells to Maintain over 98% PCE of the Small-Area Rigid Devices.

Adv Mater 2020 Dec 5;32(49):e2005153. Epub 2020 Nov 5.

CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China.

Slot-die coating is generally regarded as the most effective large-scale methodology for the fabrication of organic solar cells (OSCs). However, the corresponding device performance significantly lags behind spin-coated devices. Herein, the active layer morphology, flexible substrate properties, and the processing temperature are optimized synergistically to obtain high power conversion efficiency (PCE) for both the flexible single cells and the modules. As a result, the 1 cm flexible devices produce an excellent PCE of 12.16% as compared to 12.37% for the spin-coated small-area (0.04 cm ) rigid devices. Likewise, for modules with an area of 25 cm , an extraordinary PCE of 10.09% is observed. Hence, efficiency losses associated with the upscaling are significantly reduced by the synergistic optimization. Moreover, after 1000 bending cycles at a bending radius of 10 mm, the flexible devices still produce over 99% of their initial PCE, whereas after being stored for over 6000 h in a glove box, the PCE reaches 103% of its initial value, indicating excellent device flexibility as well as superior shelf stability. These results, thus, are a promising confirmation the great potential for upscaling of large-area OSCs in the near future.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adma.202005153DOI Listing
December 2020

Efficacy and safety of weekly carfilzomib (70 mg/m), dexamethasone, and daratumumab (KdD70) is comparable to twice-weekly KdD56 while being a more convenient dosing option: a cross-study comparison of the CANDOR and EQUULEUS studies.

Leuk Lymphoma 2021 02 28;62(2):358-367. Epub 2020 Oct 28.

John Theurer Cancer Center, Hackensack University Medical Center, Hackensack, NJ, USA.

The regimen of carfilzomib, daratumumab, and dexamethasone (KdD) shows activity in patients with relapsed/refractory multiple myeloma. KdD at the twice-weekly 56 mg/m carfilzomib dose (KdD56) was used in the randomized phase 3 CANDOR study (NCT03158688), whereas KdD at the once-weekly 70 mg/m carfilzomib dose (KdD70) was used in the phase 1 b EQUULEUS study (NCT01998971). We analyzed efficacy data from comparable CANDOR and EQUULEUS patients using inverse probability of treatment weighting (IPTW)-adjusted models. These weights were calculated from propensity scores derived to balance prespecified baseline covariates. The side-by-side and adjusted comparisons showed similar efficacy for overall response rates and progression-free survival in the two groups, with a series of sensitivity analyses showing consistent findings. Safety data were generally consistent with the known safety profiles of each individual drug. Once-weekly KdD70 is comparable to twice-weekly KdD56 in terms of efficacy and safety while being a more convenient dosing option.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/10428194.2020.1832672DOI Listing
February 2021

Numerical analysis of light reflection and transmission in poly-disperse sea fog.

Opt Express 2020 Aug;28(17):25410-25430

The presence of sea fog greatly affects both the reflected and transmitted detections when radiation propagates through targets and maritime backgrounds. Thus, the maritime target detections and the remote sensing in oceanic environments would be disturbed by the sea fog. In our work, a poly-disperse sea fog system is introduced. Such a sea fog layer comprises spherical water particles of different radii, where the radii are divided into eight radius regions. The attenuation, asymmetry factors, and absorption probabilities of the radiation interacting with sea fog particles in each radius region are computed using Mie theory. The scattering processes of the radiation in the poly-disperse sea fog layer are traced in our improved Monte Carlo (MC) simulation. This paper presents a new method (named "our method" hereafter) with the intention to provide more accurate calculations on the reflection and transmission when radiation propagates through poly-disperse sea fog media of two different refractive indices. Therein, we investigated the influence of liquid water contents and thicknesses of the poly-disperse sea fog layer on the reflectance and transmittance of the radiation. The results using our MC method compared with those using the previous MC method are also presented. Besides, with three different MC methods along with our method and the previous method, we also inspected how different MC methods affect the calculations of reflectance and transmittance, and it shows manifestation that our method has an advantage over the previous method.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.400002DOI Listing
August 2020

Modulation of Donor Alkyl Terminal Chains with the Shifting Branching Point Leads to the Optimized Morphology and Efficient All-Small-Molecule Organic Solar Cells.

ACS Appl Mater Interfaces 2020 Jun 19;12(22):25100-25107. Epub 2020 May 19.

CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China.

Terminal group modification is one of the most influential factors for small-molecular donors compared with their polymer counterparts, resulting in an opportunity to optimize the morphology of all-small-molecule organic solar cells (ASM-OSCs). In this article, we report three novel small-molecular donors with branching points at the 1-, 2-, and 3-positions in alkyl terminal chains, called , , and , respectively. Using IDIC-4Cl as the acceptor, the subtle branching position shift achieves a dramatic disparity in photovoltaic parameters, as indicated by the short circuit current () changing from 4.9 to 20.1 to 14.2 mA cm and the fill factor varying from 33.9 to 71.3 to 67.0% for , , and , respectively. The best device performance of 12.40% is obtained by the :IDIC-4Cl system, which not only ranks among the top values reported to date but also exhibits low energy loss in systems that use IDIC as acceptors. The notable device performance based on is attributed to the optimized phase morphology caused by the strong molecular crystallinity and suitable intermolecular interaction with IDIC-4Cl. These results demonstrate that suitably tuning the branching position of terminal groups could promote the high performance of ASM-OSCs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.0c03977DOI Listing
June 2020

Ultratough graphene-black phosphorus films.

Proc Natl Acad Sci U S A 2020 Apr 6;117(16):8727-8735. Epub 2020 Apr 6.

Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, People's Republic of China;

Graphene-based films with high toughness have many promising applications, especially for flexible energy storage and portable electrical devices. Achieving such high-toughness films, however, remains a challenge. The conventional mechanisms for improving toughness are crack arrest or plastic deformation. Herein we demonstrate black phosphorus (BP) functionalized graphene films with record toughness by combining crack arrest and plastic deformation. The formation of covalent bonding P-O-C between BP and graphene oxide (GO) nanosheets not only reduces the voids of GO film but also improves the alignment degree of GO nanosheets, resulting in high compactness of the GO film. After further chemical reduction and π-π stacking interactions by conjugated molecules, the alignment degree of rGO nanosheets was further improved, and the voids in lamellar graphene film were also further reduced. Then, the compactness of the resultant graphene films and the alignment degree of reduced graphene oxide nanosheets are further improved. The toughness of the graphene film reaches as high as ∼51.8 MJ m, the highest recorded to date. In situ Raman spectra and molecular dynamics simulations reveal that the record toughness is due to synergistic interactions of lubrication of BP nanosheets, P-O-C covalent bonding, and π-π stacking interactions in the resultant graphene films. Our tough black phosphorus functionalized graphene films with high tensile strength and excellent conductivity also exhibit high ambient stability and electromagnetic shielding performance. Furthermore, a supercapacitor based on the tough films demonstrated high performance and remarkable flexibility.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.1916610117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7183200PMC
April 2020

Single-Junction Organic Photovoltaic Cells with Approaching 18% Efficiency.

Adv Mater 2020 May 29;32(19):e1908205. Epub 2020 Mar 29.

State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.

Optimizing the molecular structures of organic photovoltaic (OPV) materials is one of the most effective methods to boost power conversion efficiencies (PCEs). For an excellent molecular system with a certain conjugated skeleton, fine tuning the alky chains is of considerable significance to fully explore its photovoltaic potential. In this work, the optimization of alkyl chains is performed on a chlorinated nonfullerene acceptor (NFA) named BTP-4Cl-BO (a Y6 derivative) and very impressive photovoltaic parameters in OPV cells are obtained. To get more ordered intermolecular packing, the n-undecyl is shortened at the edge of BTP-eC11 to n-nonyl and n-heptyl. As a result, the NFAs of BTP-eC9 and BTP-eC7 are synthesized. The BTP-eC7 shows relatively poor solubility and thus limits its application in device fabrication. Fortunately, the BTP-eC9 possesses good solubility and, at the same time, enhanced electron transport property than BTP-eC11. Significantly, due to the simultaneously enhanced short-circuit current density and fill factor, the BTP-eC9-based single-junction OPV cells record a maximum PCE of 17.8% and get a certified value of 17.3%. These results demonstrate that minimizing the alkyl chains to get suitable solubility and enhanced intermolecular packing has a great potential in further improving its photovoltaic performance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adma.201908205DOI Listing
May 2020

Non-Preheating Processed Quasi-2D Perovskites for Efficient and Stable Solar Cells.

Small 2020 Mar 21;16(11):e1906997. Epub 2020 Feb 21.

School of Chemistry, Beijing Advanced Innovation, Center for Biomedical Engineering, Beihang University, Beijing, 100191, China.

Although the hot-casting (HC) technique is prevalent in developing preferred crystal orientation of quasi-2D perovskite films, the difficulty of accurately controlling the thermal homogeneity of substrate is unfavorable for the reproducibility of device fabrication. Herein, a facile and effective non-preheating (NP) film-casting method is proposed to realize highly oriented quasi-2D perovskite films by replacing the butylammonium (BA ) spacer partially with methylammonium (MA ) cation as (BA) (MA) Pb I (x = 0, 0.2, 0.4, and 0.6). At the optimal x-value of 0.4, the resultant quasi-2D perovskite film possesses highly orientated crystals, associated with a dense morphology and uniform grain-size distribution. Consequently, the (BA) (MA) Pb I -based solar cells yield champion efficiencies of 15.44% with NP processing and 16.29% with HC processing, respectively. As expected, the HC-processed device shows a poor performance reproducibility compared with that of the NP film-casting method. Moreover, the unsealed device (x = 0.4) displays a better moisture stability with respect to the x = 0 stored in a 65% ± 5% relative humility chamber.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/smll.201906997DOI Listing
March 2020

Efficient Organic Solar Cells Based on Non-Fullerene Acceptors with Two Planar Thiophene-Fused Perylene Diimide Units.

ACS Appl Mater Interfaces 2020 Mar 24;12(9):10746-10754. Epub 2020 Feb 24.

Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Center for Advanced Quantum Studies, Department of Physics and Applied Optics, Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, P. R. China.

We designed and synthesized two non-fullerene acceptors (CDT-TFP and C8X-TFP), which comprise a central 4-cyclopenta[2,1-:3,4-']dithiophene (CDT) as the bridge and two thiophene-fused perylene diimide (TFP) units. The bulky side chains, such as the 4-hexylphenyl side chains, on the CDT bridge can effectively prevent the acceptor molecules from forming large aggregates, and the π-π stacking of the terminal planar TFP units can form effective electron transport pathways when blending with the donor polymers. These non-fullerene acceptors are used to fabricate organic solar cells (OSCs) by blending with the regioregular middle bandgap polymer reg-PThE. The as-cast devices based on reg-PThE:CDT-TFP show the best power conversion efficiency (PCE) of 8.36% with a of 1.10 V, of 12.43 mA cm, and an FF of 61.4%, whereas the analogue perylene diimide (PDI) dimers (CDT-PDI) that comprise two PDI units bridged with a CDT unit show only a 2.59% PCE with a of 0.92 V, of 6.82 mA cm, and an FF of 41.5%. Our results have demonstrated that the non-fullerene acceptors comprising planar PDI units can achieve excellent photovoltaic performance and provide meaningful guidelines for the design of PDI-based non-fullerene electron acceptors for efficient OSCs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.9b22927DOI Listing
March 2020

Efficient Two-Dimensional Tin Halide Perovskite Light-Emitting Diodes via a Spacer Cation Substitution Strategy.

J Phys Chem Lett 2020 Feb 28;11(3):1120-1127. Epub 2020 Jan 28.

Beijing Advanced Innovation Center for Soft Matter Science and Engineering , Beijing University of Chemical Technology , Beijing 100029 , China.

Lead halide perovskites have attracted tremendous attention because of their impressive optoelectronic properties. However, the toxicity of lead remains a bottleneck for further commercial development. Two-dimensional Ruddlesden-Popper tin-based perovskites are lead-free and more stable compared to their three-dimensional counterparts, which have great potential in the optoelectronic device field. Herein, we demonstrate high-quality two-dimensional phenylethylammonium tin-iodide perovskite (PEASnI) thin films by using toluene as the antisolvent. Furthermore, the PeLED performance is greatly improved by replacing the PEAI spacer cation with 2-thiopheneethyllamine iodide (TEAI). As a result, a TEA-based PeLED device is achieved with a low turn-on voltage of 2.3 V, a maximum luminance of 322 cd m, and maximum external quantum efficiency of 0.62%, which are the highest efficiency and brightness for pure red (emission peak = 638 nm) tin-based PeLEDs to date.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jpclett.9b03565DOI Listing
February 2020

Control of Nanomorphology in Fullerene-Free Organic Solar Cells by Lewis Acid Doping with Enhanced Photovoltaic Efficiency.

ACS Appl Mater Interfaces 2020 Jan 27;12(1):667-677. Epub 2019 Dec 27.

School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering , Beihang University , Beijing 100191 , P. R. China.

Generating desired efficiency enhancements in organic solar cells (OSCs) by charge-transfer doping requires to obtain modified optoelectronic properties while retaining the favorable nanomorphology. We report a thermally assisted doping based on Lewis acid tris(pentafluorophenyl)-borane (BCF) as a p-dopant for two groups of OSCs comprising the PBDB-TF and PBDB-T donors and a nonfullerene acceptor IT-4F. We found that the face-on molecular packing in the PBDB-TF:IT-4F blend or neat PBDB-TF donor films is favorably modified with the formation of frustrated Lewis pairs (FLPs) in the donor, which is in contrast to the hampered π-π stacking in the doped PBDB-T film. The different impacts of BCF dopants on the morphology lead to contrasting photovoltaic behaviors where the PBDB-TF-based devices receive enhanced power conversion efficiencies (PCEs) in the presence of BCF, while reduction of efficiencies is observed in the PBDB-T device. In the best doping conditions with the proposed hot-film deposition, we achieve a boosted PCE of 14.1% in PBDB-TF:IT-4F solar cells at low BCF concentrations. Based on the same fluorinated donor, the described BCF doping also applies to NF-solar cells based on the NF-acceptor Y6, leading to an increase in the PCE to 16.0%. Our results suggest that controlling the degree of FLP formation in the donor component with the addition of BCF is key to obtaining desired improvements on nanomorphology and relevant photophysical properties in OSCs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.9b17238DOI Listing
January 2020

All-small-molecule organic solar cells with over 14% efficiency by optimizing hierarchical morphologies.

Nat Commun 2019 11 26;10(1):5393. Epub 2019 Nov 26.

CAS key laboratory of nanosystem and hierarchical fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, 100190, Beijing, China.

The high efficiency all-small-molecule organic solar cells (OSCs) normally require optimized morphology in their bulk heterojunction active layers. Herein, a small-molecule donor is designed and synthesized, and single-crystal structural analyses reveal its explicit molecular planarity and compact intermolecular packing. A promising narrow bandgap small-molecule with absorption edge of more than 930 nm along with our home-designed small molecule is selected as electron acceptors. To the best of our knowledge, the binary all-small-molecule OSCs achieve the highest efficiency of 14.34% by optimizing their hierarchical morphologies, in which the donor or acceptor rich domains with size up to ca. 70 nm, and the donor crystals of tens of nanometers, together with the donor-acceptor blending, are proved coexisting in the hierarchical large domain. All-small-molecule photovoltaic system shows its promising for high performance OSCs, and our study is likely to lead to insights in relations between bulk heterojunction structure and photovoltaic performance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-019-13292-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6879588PMC
November 2019

Fine Multi-Phase Alignments in 2D Perovskite Solar Cells with Efficiency over 17% via Slow Post-Annealing.

Adv Mater 2019 Oct 2;31(42):e1903889. Epub 2019 Sep 2.

School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, 100191, China.

Layered Ruddlesden-Popper (RP) phase (2D) halide perovskites have attracted tremendous attention due to the wide tunability on their optoelectronic properties and excellent robustness in photovoltaic devices. However, charge extraction/transport and ultimate power conversion efficiency (PCE) in 2D perovskite solar cells (PSCs) are still limited by the non-eliminable quantum well effect. Here, a slow post-annealing (SPA) process is proposed for BA MA Pb I (n = 4) 2D PSCs by which a champion PCE of 17.26% is achieved with simultaneously enhanced open-circuit voltage, short-circuit current, and fill factor. Investigation with optical spectroscopy coupled with structural analyses indicates that enhanced crystal orientation and favorable alignment on the multiple perovskite phases (from the 2D phase near bottom to quasi-3D phase near top regions) is obtained with SPA treatment, which promotes carrier transport/extraction and suppresses Shockley-Read-Hall charge recombination in the solar cell. As far as it is known, the reported PCE is so far the highest efficiency in RP phase 2D PSCs based on butylamine (BA) spacers (n = 4). The SPA-processed devices exhibit a satisfactory stability with <4.5% degradation after 2000 h under N environment without encapsulation. The demonstrated process strategy offers a promising route to push forward the performance in 2D PSCs toward realistic photovoltaic applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adma.201903889DOI Listing
October 2019
-->