Single-step solution processing of small-molecule organic semiconductor field-effect transistors at high yield

Abstract

Here, we report a simple, alternative route towards high-mobility structures of the small-molecular semiconductor 5,11-bis(triethyl silylethynyl) anthradithiophene that requires one single processing step without the need for any post-deposition processing. The method relies on careful control of the casting temperature of the semiconductor and allows rapid production of transistors with uniform and reproducible device performance over large areas.

Solution-processing of semiconducting organic small molecules: what we have learnt from 5,11-bis(triethylsilylethynyl)anthradithiophene

“…This can be illustrated by work by Dickey et al who placed amorphous thin films of TES ADT into various solventvapor environments, identifying 1,2-dichloroethane as the most suitable solvent and observing the films to start crystallizing within minutes rather than days. 14 The gained speed in process did, however, come at a cost: the obtained structures displayed typically charge-carrier mobilities that were lower than those obtained for films where the a-phase was directly induced from solution, 6,7 although mobilities of B0.4 cm 2 V À1 s À1 could be induced via SVA using chloroform as solvent. 15 Other, higher-mobility TES ADT structures were obtained combining blending with an insulating polymer and SVA using 1,2-dichloroethane vapour.…”

“…For example, when spin coating this material, thin films of predominantly amorphous TES ADT are obtained. 7,8 However, over the years, a number of different crystalline phases, the a-, b-, g-, and d-phase, were reported (see Table 1), explaining why charge-carrier mobility values measured in OFETs can spread over six orders of magnitudes. 9,10 In this review, we will highlight some of the knowledge that has been gained over the years to understand specific aspects of polymorph formation in TES ADT thin films and that now permits TES ADT structures to be deposited over large areas with high reproducibility and to pattern TES ADT in a robust manner.…”

Small Molecular Aryl Acetylenes: Chemically Tailoring High‐Efficiency Organic Semiconductors for Solar Cells and Field‐Effect Transistors

“…More recently, Anthony and co‐workers revisited the use of TES‐ADT in OFET applications, exploring whether the molecular order of spin‐coated TES‐ADT films could be manipulated without the need to rely on time‐consuming post‐processing procedures. Charge‐carrier mobilities of approximately 0.08 cm 2 V −1 s −1 were obtained 28…”

On the phase behaviour of organic semiconductors

“…However, the variation that is found in TES ADT's electronic performance is significant, rendering the technological exploitation of this semiconductor effectively impossible. The low device yield and large spread in device performance can at least partially be attributed to its rich phase behaviour: TES ADT features at least four solid‐state phases depending on the processing pathway selected 13, 14. Indeed, solution casting leads to different structures from melt processing.…”

“…1). 14 Thus, judicious selection of processing conditions is required to control the crystal phase that constitutes the final architecture. Understanding the phase behaviour is thereby critical, and has been shown to allow reliable fabrication of high‐performance bottom‐gate/bottom‐contact transistors as scrutinized based on device data obtained over 90 field‐effect transistor structures 14…”