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

Four glycolated polythiophene-based organic mixed ionic-electronic conductors (OMIECs), PE2gTT, PE2gT, PT2gTT, and PT2gT are prepared by atom-efficient direct arylation polymerization, avoiding the need for toxic organometallic precursors. PE2gT, PT2gTT, and PT2gT are operable in p-type accumulation mode organic electrochemical transistors (OECTs), with PT2gT displaying the best device performance with a mu C* product figure-of-merit of 290 F cm-1 V-1 s-1. A record volumetric capacitance among p-type glycolated polythiophene OMIECs of 313 F cm-3 is observed for PE2gT, ascribed to the high proportionality of polar components in its materials design. The good OECT performance of PE2gT with mu C* = 84.2 F cm-1 V-1 s-1, comparable with state-of-the-art poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) devices, coupled with its synthetic accessibility and favorable accumulation mode operation makes PE2gT an ideal glycolated alternative to PEDOT:PSS in bioelectronics. PE2gT with the least negative threshold voltage also displays the best OECT operational cycling stability, linked to better resistance of its oxidized state against parasitic redox side reactions . Shelf life stability of OECTs stored (without bias) is observed to be better for materials with a more negative threshold voltage and higher average molecular weight (PT2gT), that are less susceptible to ambient auto-oxidation and film delamination. Four glycolated polythiophene polymers, PE2gTT, PE2gT, PT2gTT, and PT2gT are synthesized by atom-efficient direct arylation polymerization for application as active materials in organic electrochemical transistors. PT2gT exhibits the best device performance with a mu C* product figure-of-merit of 290 F cm-1 V-1 s-1, whilst volumetric capacitances of PE2gT, PT2gTT, and PT2gT are all among the highest reported for glycolated polythiophenes.image