Exceeding 200-ns Lifetimes in Polycrystalline CdTe Solar Cells
Résumé
CdTe photovoltaics has achieved one of the lowest levelized costs of electricity among all energy sources. However, for decades, carrier lifetimes have been inferior to those of other prevalent solar cell materials. This quality has inhibited common methods to improve solar cell efficiency such as back-surface fields, electron reflectors, or bifacial solar cells. In this work, we demonstrate a significant increase in carrier lifetime to values exceeding 200 ns in fully functional CdTe solar cells. The increased lifetime is achieved in these complex polycrystalline cells by realizing multiple characteristics simultaneously-the formation of oxidized tellurium species at the transparent conducting oxide interface, large CdSeTe grains at the absorber/emitter interface, and intragrain passivation in the absorber layer. The carrier lifetime is correlated to the open-circuit voltage and enables paths for back-surface manipulation and novel cell architectures to further improve CdTe photovoltaic performance.
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