All existing solar cell materials including hybrid perovskites show rather small absorption coefficient (α) of ≈104 cm−1 in the bandgap (Eg) transition region. The weak band‐edge light absorption is an essential problem, limiting conversion efficiency particularly in a tandem solar cell. Herein, all distorted chalcogenide perovskites (BaZrS3, SrZrS3, BaHfS3, and SrHfS3) are found experimentally to exhibit extraordinary high α exceeding 105 cm−1 near Eg, indicating the highest band‐edge α among all known solar cell materials. The giant absorption in the Eg region, which is consistent with the first principles, arises from the intense p–d interband transition enabled by dense S 3p valence states. For solar cell application, low‐gap BaZrS3 derivatives, Ba(Zr,Ti)S3 and BaZr(S,Se)3, are further synthesized. Among the possible candidates of top‐cell materials, an earth‐abundant and nontoxic Ba(Zr,Ti)S3 alloy shows great potential, reaching a maximum potential efficiency exceeding 38% in a chalcogenide perovskite/crystalline Si tandem architecture.

No abstract

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. Here, we have established 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 has been developed by taking incident angle, light polarization and texture effects into account. Based on the established method, we have estimated the maximum efficiencies of 13 well-studied solar cell materials [GaAs, InP, CdTe, a-HC(NH 2 ) 2 PbI 3 ] in a 1-µm-thick physical limit. Our calculation shows that over 30% efficiencies can be achieved for absorber layers with sharp absorption edges (GaAs, InP, CdTe, CuInGaSe 2 , Cu 2 ZnGeSe 4 ). 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. *fujiwara@gifu-u.ac.jp sc J kT qV J J −  

No abstract

A strong expectation exists for a two-terminal hybrid perovskite/silicon tandem solar cell for generating substantially higher output power. Nevertheless, a high tandem cell efficiency under the standard condition does not guarantee high power generation in outdoor environment due to the requirement of current matching in a tandem device. Here, we predict the global energy yields of hybrid perovskite/Si tandem and Si heterojunction single modules by establishing a new rigorous self-consistent model that performs full device simulations incorporating all fundamental time-varying parameters affecting the module power output. In particular, the temperature dependences of the optical and electrical characteristics are modeled explicitly and reliable model parameters are extracted from an industry-compatible Si heterojunction single cell (23.27% efficiency with a 120 μm wafer thickness), whereas ideal cell characteris-