Efficiency enhancement in PbS/CdS quantum dot-sensitized solar cells by plasmonic Ag nanoparticles

Semiconductor quantum dots (Q-dots) are attractive nanomaterials to be used in numerous research areas and device fabrication such as sensors, light-emitting diodes, transistors, and solar cells due to their unique optoelectronic properties. Quantum dot-sensitized solar cells (QDSSCs) have drawn considerable attention due to their cost-effectiveness and ability of multiple exciton generation and tunable energy gap of the quantum dots. In this study, plasmonic Ag colloidal nanoparticle-incorporated plasmonic TiO2 double-layer (nanofiber/nanoparticle) electrodes have been fabricated. These TiO2 electrodes were sensitized with PbS/CdS core-shell quantum dots by successive ionic layer adsorption and reaction (SILAR) technique, and QDSSCs were fabricated with polysulfide electrolyte. Cu2S was formed on brass plate and used as the counter electrode of the QDSSC. A higher power conversion efficiency of 4.09% has been obtained due to the plasmonic effect under the simulated light of 100 mW cm−2 with AM 1.5 spectral filter. The overall efficiency and short-circuit current density of the plasmonic QDSSC are enhanced by 15% and 23%, respectively, with respect to the QDSSC without Ag nanoparticles. The enhanced performance of the plasmonic QDSSC is evidently due to the enhanced optical absorption by localized surface plasmon resonance effect by the Ag nanoparticles in the TiO2 photoanode and the resulting increase in the short-circuit photocurrent.