Effect of CuBr2 salt treatment on the performance of nanocolloidal PPy:PSS multilayer thin film counter electrodes of dye‐sensitized solar cells

Abstract

ABSTRACTA thin Pt layer on fluorine‐doped tin oxide (FTO) glass is commonly used as the counter electrode (CE) for dye‐sensitized solar cells (DSCs). We have investigated thin layers on FTO glass made from spherical polypyrrole (PPy)–poly(styrene sulfonate) (PSS) nanocolloidal particles with and without treatment of CuBr2 and used them as CEs. The colloidal polymer composite (PPy:PSS) was spin‐coated at 4000 rpm, and PPy:PSS multilayer (one, three, five) films were employed as the CEs. Aqueous solutions of CuBr2 (0.5 M and 1 M) were coated onto the multilayer CEs, which increased the efficiency of DSCs. When compared with the untreated PPy:PSS counter electrodes, the CuBr2‐treated PPy:PSS films showed lower charge‐transfer resistance, higher surface roughness, and improved catalytic performance for the reduction of . The enhanced catalytic performance is attributed to the interaction of the superior electrocatalytic activity of PPy:PSS and CuBr2 salt. Under standard AM 1.5 sunlight illumination, the counter electrodes based on a single‐layer PPy:PSS composite with 0.5 M and 1 M CuBr2 salt treatment demonstrated power conversion efficiencies (PCE) of 5.8% and 5.6%, respectively. These values are significantly higher than that of the untreated PPy:PSS CE and are comparable with that of a Pt CE. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43772.