Synchronous Surface Reconstruction and Defect Passivation for High‐Performance Inorganic Perovskite Solar Cells

Abstract

commercialization due to ever-increasing power conversion efficiency (PCE), which has soared to 25.7% as of 2022. [1][2][3][4] Nonetheless, the inadequate stability caused by thermal degradation of hybrid perovskite still poses a great challenge for commercialization. [5] To circumvent this concern, all-inorganic cesium lead halide perovskites (CsPbX 3 , X = Br, I), whose volatile and vulnerable organic parts can be replaced by stable inorganic Cs + , have attracted considerable attention and exhibited great potential for both high-performance single-junction and top cells in tandem soar cells due to their unparalleled stability at high temperature. [6][7][8] In recent years, thanks to a lot of research work and incisive investigation, cesium-based inorganic perovskites have made remarkable progress in reducing the defect densities and stabilizing the black phase in the perovskite films, due especially to precursor solution optimization, [9][10][11][12] compositional engineering, [13][14][15] interface modification [16][17][18][19] and strain engineering. [6,20] Despite these unremitting efforts, the current record PCE is considerably lower than that of its hybrid counterpart and the Shockley-Queisser (S-Q) limit (≈30%). [21] This shortcoming is ascribed to a large energy loss (E loss ), suggesting that severe Shockley-Read-Hall recombination occurs in the interface or absorber layer in these solar cells, which is mainly attributed to the inevitable formation of a large number of shallow-or deeplevel defects in the crystal growth of CsPbI 3−x Br x film. [21][22][23] These undesirable defects, especially deep-level defects, are considered as nonradiative recombination centers and active sites for water adsorption. As a result, they tend to cause inferior device performance and long-term instability. [24] Thus, it is of great significance to prepare superior perovskite films with low-defect density for obtaining high-efficiency solar cells.Recently, intensive research on the deep-level physical mechanism of inorganic perovskite has led to improvements of the efficiency and stability of inorganic perovskite devices. [25][26][27][28] Lou et al. demonstrated the there are many point defects in inorganic perovskite, such as the Cs + vacancy (V Cs ) and undercoordinated Pb 2+ , etc. These inevitable defects can impair the interaction between Cs + and [PbI 6 ] 4− octahedra to some extent, thus reducing the energy difference between the black phase and yellow phase. [24,25] According to density functional theoryThe nonradiative charge recombination caused by surface defects and inferior crystalline quality are major roadblocks to further enhancing the performance of CsPbI 3−x Br x perovskite solar cells (PSCs). Theoretical calculations indicate that sodium diethyldithiocarbamate (NaDDTC), a popular bacteriostatic benign material, can initiate multiple interactions with the CsPbI 3−x Br x perovskite surface to effectively passivate the defects. The experimental results reveal that the NaDDTC can indeed passivate the elect...

Managing Multiple Halide‐Related Defects for Efficient and Stable Inorganic Perovskite Solar Cells

“…From the top‐view SEM images, the reference film exhibits compact morphology with some small grains. With these passivators, the grains were upgraded and enlarged, indicating that perovskite crystal regrowth was achieved [39–41] . The cross‐sectional SEM image of the PSCs treated with 2,6‐DAPy displays a superior monolayered polycrystalline film (Figure S5i,j).…”

Tailored Cysteine‐Derived Molecular Structures toward Efficient and Stable Inorganic Perovskite Solar Cells

“…We chose S-benzyl-l-cysteine-derived molecules as passivators to post-treat CsPbI 3−x Br x perovskite films, mainly for the following reasons: First, multiple Lewis-based functional groups (NH-, S-, and C=O) to suppress halide vacancies and coordinate with undercoordinated Pb 2+ through a typical Lewis base-acid reactions. [16,[39][40][41][42][43][44] Second, such molecules can be easily grafted with functional groups to improve passivation efficacy and hydrophobicity. In this case, considering the methoxyl group (-CH 3 O), which is a strong electron donor group, the p-𝜋 conjugation effect between the methoxyl group and the benzene ring (Ph-) can effectively enhance the electron density on the benzene ring, which will strengthen the electrostatic interaction between the benzene ring and undercoordinated Pb 2+ .…”

LiF-Modified SnO2 Electron Transport Layer Improves the Performance of Carbon-Based All-Inorganic CsPbIBr2 Perovskite Solar Cells

“…PSCs have been widely given attention because of their simple preparation process, high carrier mobility, and large absorption coefficients. − The PCE of organic–inorganic hybrid PSCs has vastly jumped from 3.8% to a certified value of 25.7% within one decade. − However, due to the easy decomposition of the organic composition, it has instability in high-humidity and high-oxygen environments. − The traditional device structure of organic–inorganic PSCs typically uses a high-cost metal electrode and expensive organic hole transport layer (HTL), which limit commercial production to some extent. − Therefore, in pursuit of PSCs with good stability, low costs, and non-toxic nature, carbon-based all-inorganic PSCs have become a new research hot spot. − …”