Constructing high-performance H3PW12O40/CoS2 counter electrodes for quantum dot sensitized solar cells by reducing the surface work function of CoS2

Abstract

A low cost H₃PW₁₂O₄₀ (PW₁₂)/CoS₂ complex is prepared and used as a counter electrode (CE) to combine with sandwich quantum dot sensitized solar cells (QDSSCs) composed of a TiO₂/CdS/CdSe/ZnS photoanode and polysulfide electrolyte to study their photovoltaic properties via a simple hydrothermal method. Under standard simulated sunlight, the photoelectric conversion efficiency (PCE) of 2%PW₁₂ (PW₁₂-2/CoS₂) doped CEs was 6.29%, which was significantly 67.7% higher than those of QDSSCs based on undoped CoS₂ CEs (3.75%). Due to the introduction of PW₁₂, the nanoparticles forming the hollow structure of CoS₂ changed from regular octahedra to rough nanoparticles, which increase the active sites. At the same time, the work function of CoS₂ decorated with PW₁₂ is decreased. This study and discovery demonstrate that POMs can be used to optimize CE materials and improve the photoelectric conversion efficiency of QDSSCs, which provide an experimental and theoretical basis for subsequent investigations.