A wide solar spectrum light harvesting Ag2Se quantum dot-sensitized porous TiO2 nanofibers as photoanode for high-performance QDSC

A wide spectrum of light harvesting silver selenide (Ag2Se) quantum dots (QDs) with an average size of ~ 5 nm has been synthesized by a low-temperature one-pot hot injection method. To finely control the size of Ag2Se QDs, oleylamine was used as the solvent, and dodecanethiol was used as the capping agent as well as a stabilizer. The prepared Ag2Se QDs were ex situ sensitized on the porous TiO2 nanofiber (NF) substrate via a direct adsorption method to use as efficient photoanode for quantum dot-sensitized solar cell (QDSC). The UV-Vis-NIR absorption and photoluminescence studies revealed that Ag2Se QD-sensitized porous TiO2 NF photoanode (Ag2Se/P-TiO2) exhibited near-infrared (NIR) absorption and fast electron kinetics. Further, the QDSC fabricated using Ag2Se/P-TiO2 NFs as the photoanode, Cu2S as the counter electrode, and liquid polysulfide (S2−/Sx2− redox couple) as the electrolyte exhibited a photoconversion efficiency of 2.50% with an improved photocurrent density of 11.12 mA/cm2.