Development of Synthetically Accessible Glycolated Polythiophenes for High-Performance Organic Electrochemical Transistors

Abstract

[Abstract]: Four glycolated polythiophene-based organic mixed ionic-electronic conductors(OMIECs), PE2gTT, PE2gT, PT2gTT, and PT2gT are prepared by atom-efficientdirect arylation polymerization, avoiding the need for toxic organometallic pre-cursors. PE2gT, PT2gTT, and PT2gT are operable in p-type accumulation modeorganic electrochemical transistors (OECTs), with PT2gT displaying the bestdevice performance with a μC* product figure-of-merit of 290 F cm−1 V−1 s−1 .A record volumetric capacitance among p-type glycolated polythiopheneOMIECs of 313 F cm−3 is observed for PE2gT, ascribed to the high proportion-ality of polar components in its materials design. The good OECT performanceof PE2gT with μC* = 84.2 F cm−1 V−1 s−1 , comparable with state-of-the-artpoly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)devices, coupled with its synthetic accessibility and favorable accumulationmode operation makes PE2gT an ideal glycolated alternative to PEDOT:PSS inbioelectronics. PE2gT with the least negative threshold voltage also displaysthe best OECT operational cycling stability, linked to better resistance ofits oxidized state against parasitic redox side reactions . Shelf life stability ofOECTs stored (without bias) is observed to be better for materials with a morenegative threshold voltage and higher average molecular weight (PT2gT),that are less susceptible to ambient auto-oxidation and film delamination.