Dual Spectral Matching in Perovskite Solar Cells via Upconverting plus Downshifting Nanoparticles

Maximizing solar cell efficiency is a critical step toward revolutionizing photovoltaic technologies and harnessing the full potential of light for energy conversion. This study investigates the incorporation of NaGdF₄:Yb³⁺,Tm³⁺@NaGdF₄:Eu³⁺ (TMN) and NaGdF₄:Yb³⁺,Er³⁺@NaGdF₄:Eu³⁺ (ERN) nanoparticles into perovskite solar cells (PSCs) to improve their power conversion efficiency. The nanoparticles were synthesized through thermolysis and characterized using multiple techniques, including photoluminescence spectroscopy, quantum yield measurements, transmission electron microscopy, X-ray diffraction, solar simulation, and external quantum efficiency assessments. These lanthanide-doped NPs exhibited strong downshifting and minor upconversion luminescence, acting like optical translators that reshape poorly absorbed light into usable wavelengths. Devices incorporating the ERN nanoparticles demonstrated a 22.19% relative increase in power conversion efficiency, while those with TMN showed a 13.23% improvement. These enhancements are attributed mainly to the effective downshifting emission of Eu³⁺ and improved surface passivation from the core-shell architecture, which together reduce recombination losses and improve charge carrier dynamics. These findings underscore the potential of photon-converting lanthanide-based materials to address spectral absorption limitations in PSCs, offering a promising route toward next-generation photovoltaic technologies.