Suppressing molecular vibrations in organic semiconductors by inducing strain.

Takayoshi Kubo,Atsushi Shishido,Yugo Okada,Junshi Soeda,Toshihiro Okamoto,Jun Takeya,Junto Tsurumi,Hiroyuki Matsui,Roger Häusermann,Chikahiko Mitsui,Yu Yamashita,Susumu Yanagisawa,Norihisa Akamatsu

doi:10.1038/ncomms11156

Abstract

Organic molecular semiconductors are solution processable, enabling the growth of large-area single-crystal semiconductors. Improving the performance of organic semiconductor devices by increasing the charge mobility is an ongoing quest, which calls for novel molecular and material design, and improved processing conditions. Here we show a method to increase the charge mobility in organic single-crystal field-effect transistors, by taking advantage of the inherent softness of organic semiconductors. We compress the crystal lattice uniaxially by bending the flexible devices, leading to an improved charge transport. The mobility increases from 9.7 to 16.5 cm2 V−1 s−1 by 70% under 3% strain. In-depth analysis indicates that compressing the crystal structure directly restricts the vibration of the molecules, thus suppresses dynamic disorder, a unique mechanism in organic semiconductors. Since strain can be easily induced during the fabrication process, we expect our method to be exploited to build high-performance organic devices.

Highlights

Organic molecular semiconductors are solution processable, enabling the growth of large-area single-crystal semiconductors
Organic semiconductors are already widely used in display applications and are expected to become even more ubiquitous when used as the building blocks for integrated circuits in applications such as radio-frequency identification tags or sensors[1]
Density functional theory (DFT) calculations and temperature-dependent measurements support the hypothesis that the suppression of molecular fluctuations is a major mechanism behind the large mobility increase

Summary

Introduction

Organic molecular semiconductors are solution processable, enabling the growth of large-area single-crystal semiconductors. We show a large effect of strain on solution-processed single-crystal organic transistors on flexible substrates. Under homogeneous strain up to 3%, induced by bending the flexible substrates, the field-effect mobility increases significantly from 9.7 to 16.5 cm[2] V À 1 s À 1.

Results

Conclusion