Low‐temperature crystallization and growth of CsPbIBr ₂ films through PbX ₂ ‐DMSO adduct towards stable and efficient carbon‐based all‐inorganic perovskite solar cells

Abstract

Summary In the realm of solar cells, currently, the carbon‐electrode‐based, all‐inorganic perovskite solar cells (C‐IPSCs) based on cesium lead mixed halide perovskites have drawn much attention. Band‐gap tunability and environmental stability of these perovskites (CsPbIBr2) have been gaining attraction as a suitable absorber material for device fabrication. Fabrication of a high‐performing and stable C‐IPSC based on CsPbIBr2 is a challenging process due to high‐temperature fabrication, poor solution deposition of perovskite film, and high recombination at perovskite/carbon interface. In this work, a simple single‐step deposition process was adopted to engineer a good quality perovskite film by replacing conventional precursors with DMSO‐adducts of lead halide (PbX2). Incorporation of the adduct‐based precursor enables crystallization of CsPbIBr2 at a low temperature (~150°C). This enhances the crystallinity of the film, improves the grain size and defects passivation which imparts endurance to the perovskite against phase change and thermal stress. Thereby, enhancing the light absorption and suppressing the non‐radiative recombination in CsPbIBr2 film. As a result, the open‐circuit voltage is enhanced up to 1.18 V and fill factor up to 57%, further improving the power conversion efficiency by 59.4% leading to a champion device efficiency of 5.9%. Adduct‐based C‐IPSC displayed substantial enhancement of ambient stability and the adduct‐based perovskite exhibited excellent thermal stability.

Recent Progress of Carbon‐Based Inorganic Perovskite Solar Cells: From Efficiency to Stability

“…Except for low costs, some special advantages of carbon electrode, such as earth abundant, highly tunable structures, chemical inertness (inherently H 2 O-resistant; inert to ion migration originating from perovskites) and compatibility with scalable techniques, suggesting their solid potential for commercialization. [27,32,[34][35][36] Carbon electrode can be used open air (or light irradiation) for a long time (hundreds of years), and has been widely used in industry and daily life. [149] The Fermi level (−5.0 eV) of carbon is close to the VBM of inorganic perovskites (such as −5.29 eV for CsPbI 3 and −5.25 eV for CsSnI 3 ), rendering it possible for hole extraction between the interface of inorganic perovskite/carbon.…”

“…Among them, carbon is thought to be the most promising counter electrode owing to its earth abundant, highly tunable structures, chemical stability, low-cost, inherently H 2 O-resistant, high carrier mobility (μ cm ), and inert to ion migration originating from perovskites. [27,32,[34][35][36] Accordingly, carbon electrode is expected to reduce production costs, simplify fabrication process, improve device stability, and ultimately achieve large-area commercialization for carbon-based inorganic PSCs (C-IPSCs).…”