Defect passivation and crystallization management enabled by thulium dopant as B-site cation for highly stable and efficiency fully inorganic perovskite solar cells with over 17% efficiency

Abstract

Despite their outstanding thermal stability and optimal band gap for tandem devices, the development of high-performance CsPbI₂Br-based inorganic perovskite solar cells is considerably hampered by defect-induced nonradiative recombination and halide ion migration. Herein, we have developed a series of CsPbI₂Br inorganic perovskite materials modified by incorporation of thulium (Tm³⁺) ions as B-site heterovalent dopants and explored their favourable impacts on the photovoltaic and stability performance of fully inorganic perovskite solar cells (FTO/SnO₂/CsPb_1-xTm_xI₂Br/CuSCN/r-GO/Au) for the first time. The champion solar cells achieve an impressive efficiency of over 17 %, with less degradations (<5%) after 400 h of operational stability and ∼30 % after 320 h of shelf stability owing to suppression of nonradiative recombination of carriers and inhibition of halide ion migration by controlling crystallization and phase stabilization. Overall, it was revealed that the Tm³⁺ ions do not play a role only elimination of ion migration and defects in perovskite film but also protects perovskite layer from moisture and continuous light illumination in fully inorganic perovskite solar cells