Temperature-resistant and highly doped Ag ₂ BeSnSe ₄ kesterite solar cell for sustainable, high-efficiency solar energy harvesting

Abstract Ag 2 BeSnSe 4 -based kesterite solar cells (KSCs) represent a bold leap toward next-generation photovoltaics, offering superior electronic and optical properties alongside remarkable thermal stability. In this work, we propose a novel device architecture: ITO/CdS/Ag 2 BeSnSe 4 /Spiro-OMeTAD/Au, designed using advanced DFT calculations and SCAPS-1D simulations. Among the Ag 2 BeSnX 4 (X = S, Se, Te) family, Ag 2 BeSnSe 4 stands out as the most suitable absorbing layer, with a direct bandgap of 1.28 eV, excellent light-harvesting capabilities, and ideal energy-level alignment. The incorporation of CdS as the electron transport layer and Spiro-OMeTAD as the hole transport layer ensures efficient charge extraction and low recombination losses, while Au and ITO serve as robust back and front contacts, respectively. High acceptor doping in Ag 2 BeSnSe 4 further boosts carrier concentration and contributes to its superior performance under elevated temperatures. Simulations reveal that an impressive PCE of 30.4% was achieved at 300 K, with efficiency remaining above 27% up to 350 K, demonstrating excellent thermal stability suitable for practical and real-world photovoltaic applications. Additionally, the use of non-toxic, earth-abundant materials makes this design not only efficient but also sustainable and scalable. The optimized cell achieves a PCE of 30.4%, Voc of 0.9565 V, Jsc of 36.1 mA.cm −2 , and FF of 87.9%, setting a new benchmark for thermally stable KSCs and paving the way for high-efficiency, eco-friendly photovoltaic technologies.