Analysis of trap distribution for smectic liquid crystals using time of flight spectroscopy

Ohno, Akira; Iino, Hiroaki; Kurotaki, Kensuke; Haruyama, Akihide; Hanna, Jun‐ichi; Dunlap, David

doi:10.1117/12.617632

Cited by 4 publications

(2 citation statements)

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“…As regards the buildup delay, one can assume that it is caused not by RC delays in the measurement circuit or waveform distortion due to space charge, but by the fact that generated carriers are trapped at the ITO electrode surface, then released by heat, and transported to the counter electrode. The delay in waveforms is reduced when Al electrodes are used instead of ITO electrodes 21,22 . In doing so, transit time was almost same as that observed with ITO electrodes and estimated waveform peak values; thus in this study, peaks of the experimental photocurrent waveforms in Figure 4 were used as transit time when calculating mobility.…”

Section: Resultssupporting

confidence: 51%

“…The delay in waveforms is reduced when Al electrodes are used instead of ITO electrodes. 21,22 In doing so, transit time was almost same as that observed with ITO electrodes and estimated waveform peak values; thus in this study, peaks of the experimental photocurrent waveforms in Figure 4 were used as transit time when calculating mobility. Thus, estimated mobility is plotted against measurement temperature and electric field strength in Figure 5 and Figure 6.…”

Section: Dependences Of Mobility On Electric Field and Temperaturementioning

confidence: 93%

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Carrier transport properties in highly ordered smectic liquid crystal phase

Nitta

Usui

Iino

et al. 2020

Electrical Engineering Japan

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We have designed and synthesized a new liquid crystalline phenylbenzothienobenzothiphene derivative, Ph‐BTBT‐4S‐3, in order to investigate the carrier transport properties in highly ordered smectic liquid crystal phase at a wide temperature range lower than room temperature enough to analyze them. Ph‐BTBT‐4S‐3 exhibits smectic E (SmE) phase, which is the one of highly ordered smectic liquid crystal phases, at the wide temperature range from 200°C to under −130°C. Thanks to its wide temperature range of SmE phase, we could reveal the carrier transport properties in the low temperature range, which were well explained on the basis of Gaussian disorder model having a Gaussian width, σ, of 87 meV, which was larger than those of typical nonpolar liquid crystals of 40−60 meV and was attributed to additional dipole of a thioether group in the side chain.

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Section: Resultssupporting

confidence: 51%

Section: Dependences Of Mobility On Electric Field and Temperaturementioning

confidence: 93%

Carrier transport properties in highly ordered smectic liquid crystal phase

Nitta

Usui

Iino

et al. 2020

Electrical Engineering Japan

Self Cite

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Interfacial trapping in an aged discotic liquid crystal semiconductor

Dawson

Patrick

Paul

et al. 2015

Journal of Applied Physics

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This study reports on time-of-flight (TOF) hole mobility measurements in aged 2,3,6,7,10,11-Hexakis(pentyloxy)triphenylene columnar liquid crystals. In contrast to the original samples reported in 2006, homeotropically aligned samples yielded TOF transients with an extended non-exponential rise. The experimental data were fit to a simple model that accurately reproduces the TOF transients assuming delayed charge release from traps near the optically excited electrode. While interfacial trapping appears only in the aged materials, the bulk mobility is similar to the pristine material. The model addresses dispersive transport in quasi-one-dimensional materials, determines the charge carrier mobility in systems with interfacial traps, and provides a method for characterizing the traps.

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