Conjugated Polymer Controlled Morphology and Charge Transport of Small-Molecule Organic Semiconductors

Zhengran He,Dawen Li,Jihua Chen,Ziyang Zhang,Sheng Bi

doi:10.1038/s41598-020-61282-x

Abstract

In this study, we report an effective approach to tune the crystallization, microstructure and charge transport of solution-processed organic semiconductors by blending with a conjugated polymer additive poly(3-hexylthiophene) (P3HT). When 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) was used as a model semiconductor material to mix with different amount of P3HT, their intermolecular interactions led to distinctive TIPS pentacene film morphologies, including randomly-oriented crystal ribbons, elongated needles with enhanced long-range order, and grass-like curved microwires with interlinkages. Each type of morphology was found to further correlate to considerably different charge transport and device performance. As compared to pristine TIPS pentacene devices, bottom-gate, top-contact OTFTs with 2% in weight P3HT additive showed a 2-fold and 5-fold improvement of average field-effect mobility and performance consistency (defined as the ratio of average mobility to the standard deviation), respectively. The improvement in transistor electrical performance can be attributed to the combined effect of enhanced crystal orientation and uniformity, as well as increased areal coverage. This work can be applied beyond the particular example demonstrated in this study and to tune the charge transport of other small-molecule organic semiconductors in general.

Highlights

In recent years, the research of high-performance, solution-processed semiconductor based organic thin film transistors (OTFTs) has attracted great attention[1,2,3,4,5,6]
The pristine TIPS pentacene formed randomly oriented crystals when grown via the method of drop casting, which resulted in anisotropic charge transport and significant device-to-device performance inconsistency of TIPS pentacene based OTFTs17
This type of morphology with improved long-range order is beneficial for charge transport and device performance of TIPS pentacene based OTFTs

Summary

Introduction

The research of high-performance, solution-processed semiconductor based organic thin film transistors (OTFTs) has attracted great attention[1,2,3,4,5,6]. Small-molecule TIPS pentacene/conjugated polymer P3HT hybrid OTFTs with a bottom-gate, top-contact configuration (Fig. 1(c)) were fabricated to characterize the mobility variation and performance consistency of the semiconductor due to the reduced crystal random orientation.

Results

Conclusion