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⁻/S_x²⁻ redox couple) as the electrolyte exhibited a photoconversion efficiency of 2.50% with an improved photocurrent density of 11.12 mA/cm².