Thiophene Polymer Semiconductors for Organic Thin‐Film Transistors

Abstract

Printed organic thin-film transistors (OTFTs) have received great interests as potentially low-cost alternative to silicon technology for application in large-area, flexible, and ultra-low-cost electronics. One of the critical materials for TFTs is semiconductor, which has a dominant impact on the transistor properties. We review here the structural studies and design of thiophene-based polymer semiconductors with respect to solution processability, ambient stability, molecular self-organization, and field-effect transistor properties for OTFT applications. We show that through judicial monomer design, delicately controlled pi-conjugation, and strategically positioned pendant side-chain distribution, novel solution-processable thiophene polymer semiconductors with excellent self-organization ability to form extended lamellar pi-stacking orders can be developed. OTFTs using semiconductors of this nature processed in ambient conditions have provided excellent field-effect transistor properties.

Structure and Morphology Control in Thin Films of Conjugated Polymers for an Improved Charge Transport

“…Firstly, extending the conjugation system and strengthening intra-chain and inter-chain interaction is a direct way to improve electronic properties. Based on the classic conjugated polymers such as P3ATs (P1), a straight strategy is inserting more conjugated moieties [3,82] such as carbon double bond (-HC=CH-, P2) [83][84][85], unsubstituted multiple or fused aromatic rings (i.e., thiophenes and thieno[3,2-b]thiophene, etc., P3-P7) [13,14,16,37,82,[86][87][88][89][90][91], other heterocyclic rings containing nitrogen(and sulfur) (P8 and P9) or selenium atoms (P10) [13,15,81,[92][93][94][95][96][97] and their combination (P11) [98]. Thus, the intra-chain conjugation is extended and strengthened by coupling with the more conjugated moieties, and the conjugation length is elongated due to the improved planarity.…”

Rational Optimization of Benzo[2,1‐b;3,4‐b′]dithiophene‐Containing Polymers for Organic Field‐Effect Transistors

“…[8] Thiophene-containing polymers have proven to be most effective. [9][10][11] This paper presents the incorporation of benzo [2,1-b; 3,4-b 0 ]dithiophene into a polythiophene as active material in a field-effect transistor (FET). The structure motif of a 2,5 connected thiophene, which is found, for example, in the well-known poly-3-hexylthiophene (P3HT), is modified by a benzo annellation.…”

“…For this reason, additional thiophene units bearing alkyl chains are incorporated into the backbone yielding polymer P2, a general concept known in the literature. [9] By optimization of the polymerization conditions, a comparable molecular weight as for polymer P1 could be obtained (M n ¼ 22 kg mol À1 ), minimizing field-effect mobility differences due to different polymer chain lengths. [14] FETs are prepared following exactly the same procedure as for P1 to ensure maximum comparability.…”

Rod–coil type miktoarm star copolymers consisting of polyfluorene and polylactide: precise synthesis and structure–morphology relationship

“…The main-chain conjugated polymer, such as poly(phenylene)s, poly(phenylenevinylene)s, poly(thiophene)s, and poly(fluorene)s, is the most important class of rod-like polymers, whose distinctive opto-electronic properties are highly interesting for creating organic devices, such as sensors, 32,33 organic light-emitting diodes (OLED), [34][35][36] organic field-effect transistors (OFET), 37,38 organic photovoltaics (OPV), [39][40][41] and memory devices. 42,43 Among them, poly(fluorene)s are highly promising materials for such applications because of their high fluorescence quantum yield and excellent charge carrier mobility.…”