Modeling of wavelength downconversion based on the Nd3+–Yb3+ system for improving c-Si solar cell performance

A resonant two-step quantum cutting process in a wavelength downconverter of Nd3+–Yb3+-codoped fluoroindogallate glasses is investigated by establishing and solving the simulated theoretical model of rate equations and power density propagation equations. Based on the optimized Nd3+ and Yb3+ concentration and the thickness of the wavelength downconverter, a total power efficiency of 128% and a total quantum efficiency of 176% have been obtained. A conversion efficiency of 18.69% for a c-Si solar cell under the modified spectrum relative to 16.46% under the normalized AM1.5G spectrum have been obtained through PC1D simulations, and the relative conversion efficiency reaches 1.14. Our results and techniques provide a framework for investigating and optimizing rare-earth-doped wavelength downconverters, potentially enabling a crystalline Si solar cell with an efficiency improvement. (paper)