Inorganic CsPbBr₃ Perovskite Nanocrystals as Interfacial Ion Reservoirs to Stabilize FAPbI₃ Perovskite for Efficient Photovoltaics

Abstract

Bulk lead halide perovskite films with unique optoelectronic properties and facile low‐cost processing methods are promising for various optoelectronic applications including photovoltaics. Solution‐processed colloidal inorganic perovskite nanocrystals with higher crystallinity hold good potential for devices with better stability and optoelectronic properties. To address phase stability and defect passivation issues in black phase FAPbI3 perovskite, all‐inorganic perovskite CsPbBr3 nanocrystals (CPB NCs) are adapted as an effective modifier to form CPB NC‐treated FAPbI3 perovskite films (noted as CPB NC‐FAPbI3). It is identified in this study that, the incorporated CsPbBr3 NCs not only act as surface additives for the bulk perovskite films, but can also serve as ion reservoirs to supply both cation and halide exchanges at the interface. This two‐way ion exchange in CPB NC‐FAPbI3 samples leads to the formation of a compositional gradient as FA1−xCsxPbI3−yBry layers on the bulk perovskite film surface with vertically varied x and y values. Defects at interfaces and grain boundaries are therefore effectively passivated, leading to improved stability and charge carrier dynamics. As a result, the CPB NC‐FAPbI3 perovskite based solar cells exhibit overall enhancements in device efficiency and operational stability.

Recent progress of copper halide perovskites: properties, synthesis and applications

“…toxicity of lead leakage 17,18 and poor material stability from the intrinsic ionic properties of halide perovskites. 19 Resolving these issues has attracted significant research efforts (with some success); [20][21][22] however, the replacement of toxic lead with other metal ions in perovskite materials will more thoroughly address these limitations.…”

Crystallization Dynamic Control of Perovskite Films with Suppressed Phase Transition and Reduced Defects for Highly Efficient and Stable All-Inorganic Perovskite Solar Cells

“…Due to their distinctive optoelectronic characteristics, lead halide perovskites have become promising photovoltaic materials. − The associated perovskite solar cells’ (PSCs) measured power conversion efficiency (PCE) has increased to more than 25.7%, − highlighting the considerable potential for its commercial applications. , However, most highly efficient PSCs tend to degrade quickly at high temperatures due to the organic cationic methylamine (MA) and formamidine (FA) constituents utilized, which affects their long-term stability . Consequently, various all-inorganic, high-temperature resistant perovskite materials (CsPbX 3 ) have been developed to prepare long-term stability PSCs. − Among CsPbX 3 -based PSCs, the black phase CsPbI 3 has the best device PCE due to its acceptable bandgap (1.73 eV). , However, the thermo-dynamically unstable α-CsPbI 3 is highly sensitive to water at room temperature, which is easily transformed into the inert yellow phase δ-CsPbI 3 , resulting in the long term stability of PSCs being limited.…”

Halides‐Enhanced Buried Interfaces for Stable and Extremely Low‐Voltage‐Deficit Perovskite Solar Cells

“…To understand the origins of the V oc enhancement in F-SnO 2 -based devices, [56] the trap density was evaluated through the space charge limiting current with a device of FTO/SnO 2 /perovskite/PCBM/Ag (Figure S36, Supporting Information). The device with F-SnO 2 showed a smaller trap-filled limit voltages (V TFL ) of 0.148 V compared to the control (0.438 V), suggesting lower trap densities and suppressed NRR in F-SnO 2based devices.…”