Device engineering of lead‐free FaCsSnI 3 /Cs 2 AgBiI 6 ‐based dual‐absorber perovskite solar cell architecture for powering next‐generation wireless networks

Solar‐powered devices, such as wireless networks, are a crucial component of the Internet of Things (IoT). Designing and creating a solar cell architecture with an extended light absorption regime at a reasonable cost is therefore exceedingly important. All inorganic bismuth‐based Cs 2 AgBiI 6 planar perovskite solar cells (PSCs) have garnered enormous significance due to their exceptional stability against oxygen, heat, and moisture. However, the power conversion efficiencies of Cs 2 AgBiI 6 ‐based planar PSCs remain relatively low, primarily due to their limited light absorption range and interfacial charge recombination losses. This issue can be effectively addressed using a novel multi‐absorber architecture that incorporates dual absorbers with both lower band gap and wider band gap materials. This approach extends the light absorption range, enabling maximal utilization of the solar spectrum. Therefore, this article incorporates numerical modeling and guided optimization of ITO/ETL/Cs 2 AgBiI 6 /Fa 0.75 Cs 0.25 SnI 3 /HTL/Ag dual absorber‐based heterojunction structure to improvise the power conversion efficiency of Cs 2 AgBiI 6 ‐based single‐absorber PSCs. The proposed configuration employs dual perovskite absorber layers (PALs) consisting of wide band gap Cs 2 AgBiI 6 (1.6 eV) as the top absorber layer along with narrow bandgap Fa 0.75 Cs 0.25 SnI 3 (1.27 eV) to act as the bottom absorber layer. Before evaluating the bilayer configuration, two standalone PSC architectures, namely, ITO/ETL/Fa 0.75 Cs 0.25 SnI 3 /HTL/Ag (D1)‐ and ITO/ETL/Cs 2 AgBiI 6 /HTL/Ag (D2)‐based PSC have been simulated and computed to perfectly fit the earlier anticipated state of art results. After effective validation of the photovoltaic parameters of the standalone architectures, both the absorber layers are appraised to constitute a dual active layer configuration ITO/ETL/Cs 2 AgBiI 6 /Fa 0.75 Cs 0.25 SnI 3 /HTL/Ag (D3) maintaining the overall absorber layer width constant to elevate the overall solar cell efficiency. Herein, a combination of various competent hole transport layers (HTLs) such as CBTS, CFTS, Cu 2 O, CuI, CuO, CuSCN, P3HT, PEDOT:PSS, and Spiro‐OMeTAD, as well as electron transport layers (ETLs) like C 60 , CeO 2 , IgZo, PCBM, TiO 2 , WS 2 , and ZnO, are adopted and compared to attain highly efficient bilayer PSC configuration. The crucial variables of all ETL‐ and HTL‐based proposed bilayer solar cell configurations including the thickness of PALs, the width