Abstract
Abstract
Electrical conductivity is a critical parameter for conductive polymers. Conventional strategies of solvent-doping and solvent post-treatment have improved the conductivity of pure free-standing PEDOT:PSS films from ~2 to ~1500 S cm-1, yet substantial room for improvement remains. The solvothermal technique, with its unique advantage of high temperature and self-generated pressure, demonstrates significant potential for further enhancing the conductivity of free-standing PEDOT:PSS thick films. Herein, we systematically investigated the solvothermal effects of methanol (MeOH), N, N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) on the conductivity of free-standing PEDOT:PSS thick films. The obtained free-standing PEDOT:PSS films exhibited high conductivities of 2958 S cm-1 (MeOH), 2528 S cm-1 (DMF), and 2438 S cm-1 (DMSO), respectively. This exceptional performance arise from the synergistic effect of enhanced π-π stacking, increased crystallinity and aggregation of PEDOT nanocrystals, the transition of PEDOT chains from a neutral state to a bipolaronic state, structural transformation of PEDOT from benzene to quinone forms, and massive PSS removement. What excites us is that the PEDOT film achieved a capacitance of 251 F cm-3 due to the optimization of the preparation process, significantly surpassing previously reported values. This study verifies the universality of solvothermal strategy with common organic solvents for improving the conductivity of PEDOT:PSS thick film and highlights its great promise for energy storage field.