Tuning charge carrier transport and optical birefringence in liquid-crystalline thin films: A new design space for organic light-emitting diodes.

Sci Rep 2018 01 15;8(1):699. Epub 2018 Jan 15.

Department of Physics, Kent State University, Kent, OH, 44242, USA.

Liquid-crystalline organic semiconductors exhibit unique properties that make them highly interesting for organic optoelectronic applications. Their optical and electrical anisotropies and the possibility to control the alignment of the liquid-crystalline semiconductor allow not only to optimize charge carrier transport, but to tune the optical property of organic thin-film devices as well. In this study, the molecular orientation in a liquid-crystalline semiconductor film is tuned by a novel blading process as well as by different annealing protocols. The altered alignment is verified by cross-polarized optical microscopy and spectroscopic ellipsometry. It is shown that a change in alignment of the liquid-crystalline semiconductor improves charge transport in single charge carrier devices profoundly. Comparing the current-voltage characteristics of single charge carrier devices with simulations shows an excellent agreement and from this an in-depth understanding of single charge carrier transport in two-terminal devices is obtained. Finally, p-i-n type organic light-emitting diodes (OLEDs) compatible with vacuum processing techniques used in state-of-the-art OLEDs are demonstrated employing liquid-crystalline host matrix in the emission layer.

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-018-19157-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5768873PMC
January 2018
35 Reads

Publication Analysis

Top Keywords

charge carrier
20
carrier transport
12
single charge
12
liquid-crystalline semiconductor
12
light-emitting diodes
8
alignment liquid-crystalline
8
organic light-emitting
8
carrier devices
8
liquid-crystalline
6
carrier
5
organic
5
charge
5
verified cross-polarized
4
alignment verified
4
altered alignment
4
cross-polarized optical
4
spectroscopic ellipsometry
4
improves charge
4
charge transport
4
transport single
4

References

(Supplied by CrossRef)

Y Diao et al.
Nat. Mater. 2013

T Izawa et al.
Adv. Mater. 2008

VC Sundar et al.
Science 2004

M Mesta et al.
Nat. Mater. 2013

Y Yuan et al.
Nat. Commun. 2014

G Giri et al.
Nature 2011

DJ Gundlach et al.
Nat. Mater. 2008

MC Gather et al.
Adv. Mater. 2011

S Reineke et al.
Rev. Mod. Phys. 2013

Y Liu et al.
J. Mater. Chem. C 2014

JY Xue et al.
Chem. Sci. 2016

Similar Publications