Thiazole Imide‐Based All‐Acceptor Homopolymer: Achieving High‐Performance Unipolar Electron Transport in Organic Thin‐Film Transistors

Abstract

High-performance unipolar n-type polymer semiconductors are critical for advancing the field of organic electronics, which relies on the design and synthesis of new electron-deficient building blocks with good solubilizing capability, favorable geometry, and optimized electrical properties. Herein, two novel imide-functionalized thiazoles, 5,5'-bithiazole-4,4'-dicarboxyimide (BTzI) and 2,2'-bithiazolothienyl-4,4',10,10'-tetracarboxydiimide (DTzTI), are successfully synthesized. Single crystal analysis and physicochemical study reveal that DTzTI is an excellent building block for constructing all-acceptor homopolymers, and the resulting polymer poly(2,2'-bithiazolothienyl-4,4',10,10'-tetracarboxydiimide) (PDTzTI) exhibits unipolar n-type transport with a remarkable electron mobility (μ ) of 1.61 cm V s , low off-currents (I ) of 10 -10 A, and substantial current on/off ratios (I /I ) of 10 -10 in organic thin-film transistors. The all-acceptor homopolymer shows distinctive advantages over prevailing n-type donor-acceptor copolymers, which suffer from ambipolar transport with high I s > 10 A and small I /I s < 10 . The results demonstrate that the all-acceptor approach is superior to the donor-acceptor one, which results in unipolar electron transport with more ideal transistor performance characteristics.

Fluorine Substituted Bithiophene Imide‐Based n‐Type Polymer Semiconductor for High‐Performance Organic Thin‐Film Transistors and All‐Polymer Solar Cells

“…Coupling 6 with 2‐(trimethylstannyl)thiophene‐3‐carboxylate yielded tetramethyl 3”,4'‐difluoro‐[2,2':5',2”:5”,2”'‐quaterthiophene]‐3,3',3”',4”‐tetracarboxylate 7 , which was subjected to hydrolysis to provide 3”,4'‐difluoro‐[2,2':5',2”:5”,2”'‐quaterthiophene]‐3,3',3”',4”‐tetracarboxylic acid 8 . The imide s‐FBTI2 was then prepared by a simple and efficient method, which was readily brominated to afford the dibrominated monomer s‐FBTI2‐Br in an excellent yield (95%). The successful fluorination of BTI developed here should be informative for synthesizing other F‐functionalized electron‐deficient building blocks.…”

“…We recently devised a series of ladder‐type BTI‐based derivatives BTIn up to 15 rings and 5 imide groups in a row (Figure ) . In addition to ring fusion, the β‐ position can also be readily modified by incorporating electron withdrawing groups (or moieties) to generate “stronger acceptors” (Figure ), which are well desired for constructing n‐type semiconductors. Fluorination of π‐conjugated systems has been widely used in organic electronics community to optimize the optoelectronic properties of semiconductors by exploiting the high electronegativity and small size of the F atom .…”

Imide‐Functionalized Polymer Semiconductors

“…In another report, a more electron‐deficient thiazole was used to replace one thiophene in BTI to afford a BTI derivative, thiazolothienyl imide (TzTI), which should be a stronger acceptor than BTI. The unique geometry and physicochemical properties of TzTI enables the development of all‐acceptor type homopolymers, and the resulting polymer 68 based on the TzTI dimer exhibited a remarkable unipolar μ e,OTFT of 1.61 cm 2 V −1 s −1 , low off‐currents ( I off ) of 10 −10 –10 −11 A, and substantial current I on / I off ratios of 10 7 –10 8 in OTFT devices . A series of fused BTI‐based ladder‐type small molecular heteroarenes (BTI1‐5) with up to 15 rings and 5 imide groups were also synthesized .…”

New Conjugated Polymers Based on Dithieno[2,3‐e:3′,2′‐g]Isoindole‐7,9(8H)‐Dione Derivatives for Applications in Nonfullerene Polymer Solar Cells

“…The imide functionalized unit has been used as an acceptor unit for the development of wide bandgap polymers and showed the ambipolar transport characteristics . In this regard, we have designed and synthesized two A1–D1–A2–D1 conjugated copolymers having the same dithieno[2,3‐e:3′,2′‐g]isoindole‐7,9(8H)‐dione (DTID) acceptor (A1) and thiophene donor (D1) and different A2 acceptor units, i.e., benzothiadiazole (BT) and fluorinated benzothiadiazole (f‐BT) denoted as P113 and P114, respectively, and their optical and electrochemical properties were investigated.…”