The design and performance optimization of all-inorganic CsPbIBr2/CsSnI3 heterojunction perovskite solar cells

• CsPbIBr 2 /CsSnI 3 PSC extends the absorption spectrum into the near infrared region. • CsSnI 3 replaces the organic HTL to form an all-inorganic PSC . • Optimized CsPbIBr 2 /CsSnI 3 heterojunction laminated solar cell PCEreaches 36.41%. With the fast growth of perovskite solar cells (PSCs), inorganic perovskite, represented by Cs-based perovskite, consistently surpasses organic perovskite solar cells in regards of photovoltaic performance. Among them, CsPbIBr 2 materials stand out for their excellent efficiency and stability in all-inorganic PSCs. Unfortunately, poor solar energy utilization results from the CsPbIBr 2 ′s wide band gap, which severely limits light harvesting. This work proposes an all-inorganic CsPbIBr 2 /CsSnI 3 heterojunction using CsSnI 3 instead of HTL based on the matched band structure of CsSnI 3 and CsPbIBr 2 , then simulations and optimizes it using SCAPS-1D software to increase solar energy utilization and cell efficiency. The results show that the CsPbIBr 2 /CsSnI 3 perovskite heterojunction PSC extends the absorption spectral wavelength range from 600 nm in the visible area to 960 nm in the near-infrared region, which greatly improves solar energy utilization and is more favorable to photogenerated carrier migration. The device's performance is ideal after optimization when Voc = 1.0344 V, Jsc = 39.36 mA/cm 2 , FF = 89.43%, and PCE = 36.41%. The device efficiency of the optimized CsPbIBr 2 /CsSnI 3 heterojunction is 36.41%, which is significantly higher than the PCE of 5.45% for a single layer of CsPbIBr 2 . Moreover, the CsPbIBr 2 /CsSnI 3 solar cell can respond to near-infrared light, enabling it to generate power at night. Consequently, this work reveals that the constructed CsPbIBr 2 /CsSnI 3 heterojunction PSCs can enable the bright future of Cs-based inorganic PSCs for practical applications in photovoltaics and optoelectronics.