It is very significant to understand the formation of perovskite crystals from the precursor solution and construct high-quality films to achieve highly efficient perovskite solar cells (PSCs). Here, we have revealed a colloidal strategy to prepare compact monolayer perovskite films by controlling the size of colloidal clusters in the perovskite precursor. Under the action of the coordination interaction, the introduction of CH₃NH₃Cl (MACl) into the standard perovskite precursor significantly increases the size of colloidal clusters. Meanwhile, N-dimethyl sulfoxide (DMSO) is further employed to stabilize the characteristics of the colloidal clusters and improve the reproducibility of the anti-solvent method. The large colloidal clusters can be orderly arranged on the substrate by spin-coating to form intermediate phase monolayer films, which grow to form large grains with an average size of 3 μm. Due to the much lower trap-state density and higher crystallinity of the monolayer perovskite films, a power conversion efficiency (PCE) of 19.14% has been achieved. This study sheds light on the conversion mechanism of perovskite crystals from the colloidal precursor to solid films, and paves the way for further improvement of high-quality perovskite films that can lead to high performance devices.

中文翻译：

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面向高性能钙钛矿太阳能电池的单层CH ₃ NH ₃ PbI ₃膜的胶体工程

了解前驱体溶液中钙钛矿晶体的形成并构建高质量的薄膜以实现高效钙钛矿太阳能电池（PSC），这一点非常重要。在这里，我们揭示了通过控制钙钛矿前体中胶体簇的大小来制备紧凑的单层钙钛矿膜的胶体策略。在配位相互作用的作用下，将CH ₃ NH ₃ Cl（MACl）引入标准钙钛矿前体中会显着增加胶体团簇的大小。同时，N-二甲亚砜（DMSO）进一步用于稳定胶体团簇的特性并提高抗溶剂法的重现性。可以通过旋涂将大的胶体团簇有序地排列在基板上，以形成中间相单层膜，该中间相单层膜可以生长以形成平均粒径为3μm的大晶粒。由于单层钙钛矿薄膜的陷阱态密度低得多且结晶度更高，因此实现了19.14％的功率转换效率（PCE）。这项研究揭示了钙钛矿晶体从胶体前体到固体膜的转化机理，并为进一步改进可导致高性能器件的高质量钙钛矿膜铺平了道路。