Sensitivity analysis of the theoretical performance of semiconductor upconversion nanostructures

摘要

Detailed balance models of the performance of upconverter-backed single-junction solar cells show significantly improved solar cell efficiency of over 47% under 1-sun and 63% under concentration. Realizing these predicted gains, however, requires finding or engineering materials that can realize the upconversion performance needed. Semiconductor upconversion heterostructures show the greatest potential in this respect, with over 39% solar cell efficiency predicted using a kinetic rate model to describe the upconverter photophysics. Although the kinetic rate model used was based on realistic material parameters, material design and engineering requires trade-offs that should be informed by a sensitivity analysis of the upconverter kinetic rate model assumptions. Here, we analyze the robustness of the kinetic rate model by considering how the internal upconversion quantum efficiency is affected by variations in the solar spectrum splitting (i.e., photon absorption energy ranges), upconverter absorption cross section, carrier relaxation and recombination rates, and solar concentration. We further analyze the upconverter-backed solar cell performance as a function of these variations using detailed balance methods. The results show that the theoretical performance of this upconversion paradigm under concentrated sunlight agrees with previous models and exceeds 60% solar energy conversion efficiency. More importantly, the results show that the predicted performance is relatively insensitive to the assumptions made in the model, suggesting that practical realization of such a semiconductor upconverter heterostructure paradigm is possible.