Maximum Efficiencies and Performance-Limiting Factors of Inorganic and Hybrid Perovskite Solar Cells

The Shockley and Queisser limit, a well-known efficiency limit for a solar cell, is based on unrealistic physical assumptions and its maximum limit is seriously overestimated. To understand the power loss mechanisms of record efficiency cells, a more rigorous approach is necessary. We establish a formalism that can accurately predict absolute performance limits of solar cells in conventional thin-film form. In particular, a formulation for a strict evaluation of the saturation current in a nonblackbody solar cell is developed by taking the incident angle, light polarization, and texture effects into account. Based on the established method, we estimate the maximum efficiencies of 13 well-studied solar cell materials [GaAs, InP, CdTe, a-Si:H, CuInSe2, CuGaSe2, CuInGaSe2, Cu2ZnSnSe4, Cu2ZnSnS4, Cu2ZnSn(S,Se)(4), Cu2ZnGeSe4, CH3NH3 PbI3, HC(NH2)(2)PbI3] in a 1-mu m-thick physical limit. Our calculation shows that over 30% efficiencies can be achieved for absorber layers with sharp absorption edges (GaAs, InP, CdTe, CuInGaSe2, Cu2ZnGeSe4). Nevertheless, many record efficiency polycrystalline solar cells, including hybrid perovskites, are limited by open-circuit voltage and fill-factor losses. We show that the maximum conversion efficiencies described here present alternative limits that can predict the power generation of real-world solar cells.