“…However, the high cost, abundance deficiency, and corrosion in triiodide solution make Pt unsuitable for commercial purpose of DSSCs [3]. Therefore, many functional materials have been investigated for Pt-free counter electrodes, such as carbon materials [4], conducting polymers [5][6][7][8][9][10][11][12][13], some metal-based inorganic compounds [14][15][16][17], and composite materials [18][19][20]. As a substituted polythiophene, poly(3,4-ethylenedioxythiophene) (PEDOT) has been widely studied due to its high conductivity, electrochemical stability, catalytic ability, and easy fabrication in large scale.…”