LAUSR

Abstract Developing low-cost and high-performance Pt-free counter electrodes (CE) is of vital significance for the commercial DSSCs application. Herein, three kinds of transition metal phosphates (Ni3(PO4)2, Co3(PO4)2, Ag3PO4) were separately composited with the conductive binder PEDOT and the yielded hybrid films were successfully used as counter electrodes for DSSCs. It is found that the content of the phosphates forcefully affects the performance of the composite CEs. Among these phosphates-PEDOT hybrid films, the Ni3(PO4)2-based composite CE with 50 mg/ml Ni3(PO4)2 in PEDOT precursor solution, shows the best power conversion efficiency (PCE) of 6.412%, which is higher than the original PEDOT PCE (5.443%) and comparable with the conventional magnetron sputtering Pt PCE (6.307%). Various analytical methods were utilized to investigate the origin of the improved power conversion efficiency (PCE). The results demonstrate that large active area, low charge transfer resistance and excellent electrocatalytic activity contribute to the outstanding PCE. Moreover, the optimizing PEDOT-Ni3(PO4)2-50 hybrid film CE exhibits good stability in the practical operation, demonstrating its potential for replacing the rare and expensive Pt CE.