Nonradiative Recombination Dominates Voltage Losses in Cu(In,Ga)Se2 Solar Cells Fabricated Using Different Methods: Article No. 2300075

Voltage losses reduce the photovoltaic conversion efficiency of thin-film solar cells, and are a primary efficiency limitation in Cu(In,Ga)Se2. This work presents a voltage loss analysis of Cu(In,Ga)Se2 solar cells fabricated at three institutions with variation in process, bandgap, absorber structure, post deposition treatment (PDT), and efficiency. Non-radiative voltage losses due to Shockley-Read-Hall (SRH) charge carrier recombination dominate and constitute >75% of the total compared to <25% from radiative voltage losses. The radiative voltage loss results from non-ideal absorption and carriers in band tails that stem from local composition-driven potential fluctuations. We show that significant bulk lifetime improvements are achieved for all alkali PDT processed absorbers, chiefly associated with reductions in non-radiative recombination. Primary voltage loss contributions-radiative and non-radiative-change little across fabrication processes, but variation in sub-mechanisms-bulk lifetime, net acceptor concentration, and interface recombination-differentiate non-radiative loss pathways in this series of solar cells.