Band-like transport in small-molecule thin films toward high mobility and ultrahigh detectivity phototransistor arrays

Wenping Hu,Zhao-Yang Zhang,Mianzeng Zhong,Jie Liu,Saeed Amirjalayer,Tao Li,Huanli Dong,Deyang Ji,Harald Fuchs,Zhongming Wei,Xianhui Huang

doi:10.1038/s41467-018-07943-y

Abstract

With the fast development of organic electronics, organic semiconductors have been extensively studied for various optoelectronic applications, among which organic phototransistors recently emerged as one of the most promising light signal detectors. However, it is still a big challenge to endow organic phototransistors with both high mobility and high light-sensitivity because the low mobility of most organic photoresponsive materials limits the efficiency of transporting and collecting charge carriers. We herein report band-like charge transport in vacuum-deposited small-molecule thin films for organic phototransistor arrays which can be operated at very low dark currents (~10−12 A). Both high mobility and excellent optical figures of merit including photosensitivity, photoresponsivity and detectivity are achieved, wherein, unprecedentedly, a detectivity greater than 1017 cm Hz1/2 W−1 is obtained. All these key parameters are superior to state-of-the-art organic phototransistors, implying a great potential in optoelectronic applications.

Highlights

With the fast development of organic electronics, organic semiconductors have been extensively studied for various optoelectronic applications, among which organic phototransistors recently emerged as one of the most promising light signal detectors
Acenes are typical small molecules that have been extensively studied for organic electronics
It has been verified that extending the π-conjugation system can reduce the reorganization energy and enhance electronic coupling for higher charge carrier mobility[10], which, is normally at the expense of the environmental stability and optoelectronic properties

Summary

Introduction

With the fast development of organic electronics, organic semiconductors have been extensively studied for various optoelectronic applications, among which organic phototransistors recently emerged as one of the most promising light signal detectors. We report band-like charge transport in vacuum-deposited small-molecule thin films for organic phototransistor arrays which can be operated at very low dark currents (~10−12 A) Both high mobility and excellent optical figures of merit including photosensitivity, photoresponsivity and detectivity are achieved, wherein, unprecedentedly, a detectivity greater than 1017 cm Hz1/2 W−1 is obtained. All these key parameters are superior to state-of-the-art organic phototransistors, implying a great potential in optoelectronic applications. It is noteworthy that the small-molecule thinfilm field-effect transistors show “band-like” charge transport, implying the highly crystalline nature of the thin films Both high mobility and excellent optical figures of merit are successfully obtained, showing a prospect of high-performance OPTs for both experimental research and practical applications

Methods

Results

Conclusion