High-Performance Semiconducting Polythiophenes for Organic Thin-Film Transistors

Abstract

Conjugated polymers have been widely studied as potential semiconductor materials for organic thin-film transistors (TFTs). However, they have provided functionally poor transistor properties when the TFTs are fabricated in air. We have developed a class of liquid crystalline regioregular polythiophenes, PQTs, that possess sufficient air stability to enable achievement of excellent TFT properties under ambient conditions. These polythiophenes exhibit unique self-assembly ability and form highly structured thin films when deposited from solution under appropriate conditions. TFTs fabricated in air with PQT channel layers have provided high field-effect mobility to 0.14 cm2 V-1 s-1 and high current modulation to over 107, together with other desirable transistor properties. These high-performance polythiophenes will therefore help bring the long-standing concept of low-cost organic/polymer transistor circuits closer to commercial reality.

Soluble fullerene derivatives: The effect of electronic structure on transistor performance and air stability

“…Previous efforts in the development of air-stable p-channel organic semiconductors have yielded high performance materials. [3][4][5] However, producing solution processable air-stable n-channel devices with equivalent performance has only been achieved in the last few years [6][7][8] and remains challenging for many families of materials.…”

Incremental optimization in donor polymers for bulk heterojunction organic solar cells exhibiting high performance

“…In this context, different approaches have been used to achieve optimal morphology, such as thermal 72 and solvent 42 annealing and usage of additives. 44 The ultimate goal of these efforts is to control the domain size leading to the formation of interpenetrating network for an effective charge transport. The effectiveness of these approaches largely depends on the nature of donor polymers, for example, while the thermal annealing process was effective in P3HT/PCBM system, it failed completely in PTBx polymer system, leading to a dramatic decrease in device performance.…”

“…Therefore, a number of additives such as alkanethiols, 44 dichlorobenzene, 74 diethylene glycol, 76 1,8-diiodoalkane, 59 1-chloronaphthalene, 77 and so forth have been investigated for different polymer-fullerene systems. Transmission electron microscopy (TEM) analysis on PTB7 polymer showed obvious and large phase separation when it was blended with PC 71 BM in chlorobenzene (CB) without any additives, but a very uniform morphology was observed upon addition of DIO additive (Fig.…”

Imaging the domain structure of organic semiconductor films

“…Transistors based on PQT-12 have achieved field-effect mobilities of order 0.2 cm 2 /Vs. 23 A relatively monodisperse sample of PQT-12 consisting of mostly oligomers of two quarterthiophene units were studied by Kuehn et al as a model system possessing some polymeric properties but also sharing characteristics with small molecules (notably reduced complications arising from polydispersity). With the use of polarized NSOM measurements Kuehn et al have been able to map the relative dichroism and dichroic orientation of polycrystalline oligo-PQT-12 films with 100-nm resolution, see Figure 3.…”