Terbium-Doped and Dual-Passivated γ-CsPb(I<sub>1-</sub> <sub>x</sub> Br<sub>x</sub> )<sub>3</sub> Inorganic Perovskite Solar Cells with Improved Air Thermal Stability and High Efficiency.

Mali, Sawanta S; Patil, Jyoti V; Rondiya, Sachin R; Dzade, Nelson Y; Steele, Julian A; Nazeeruddin, Mohammad Khaja; Patil, Pramod S; Hong, Chang Kook · Adv Mater · 2022

basic_science · Level V

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Abstract

Realizing photoactive and thermodynamically stable all-inorganic perovskite solar cells (PSCs) remains a challenging task within halide perovskite photovoltaic (PV) research. Here, a dual strategy for realizing efficient inorganic mixed halide perovskite PV devices based on a terbium-doped solar absorber, that is, CsPb<sub>1-</sub> <sub>x</sub> Tb<sub>x</sub> I<sub>2</sub> Br, is reported, which undertakes a bulk and surface passivation treatment in the form of CsPb<sub>1-</sub> <sub>x</sub> Tb<sub>x</sub> I<sub>2</sub> Br quantum dots, to maintain a photoactive γ-phase under ambient conditions and with significantly improved operational stability. Devices fabricated from these air-processed perovskite thin films exhibit an air-stable power conversion efficiency (PCE) that reaches 17.51% (small-area devices) with negligible hysteresis and maintains >90% of the initial efficiency when operating for 600 h under harsh environmental conditions, stemming from the combined effects of the dual-protection strategy. This approach is further examined within large-area PSC modules (19.8 cm<sup>2</sup> active area) to realize 10.94% PCE and >30 days ambient stability, as well as within low-bandgap γ-CsPb<sub>0.95</sub> Tb<sub>0.05</sub> I<sub>2.5</sub> Br<sub>0.5</sub> (E<sub>g</sub>  = 1.73 eV) materials, yielding 19.01% (18.43% certified) PCE.