Organometallic Compound Stabilizes All‐Inorganic Tin‐Based Perovskite Nanocrystals Against Antisolvent Post‐Treatment

Abstract The isolation and purification of all‐inorganic Sn‐based perovskite nanocrystals (PNCs) remain troublesome, as common antisolvents accelerate the collapse of the optically active perovskite structure. Here, we mitigate such instabilities and endow strong resistance to antisolvent by incorporating the organometallic compound zinc diethyldithiocarbamate, Zn(DDTC) 2 , during the solution‐based synthesis of all‐inorganic CsSnI 3 nanocrystals. Thiourea is shown to form through the thermal‐driven conversion of Zn(DDTC) 2 during synthesis, which binds to un‐passivated Sn sites on the crystal surface and shields it from irreversible oxidation reactions. The CsSnI 3 PNCs capped with thiourea show great stability after two purification cycles using methyl acetate, with negligible change in morphology, phase, and optical properties. Moreover, the modified PNCs are resistant to other commonly used antisolvents, like ethyl acetate, 1‐pentanol, and isopropanol, offering a platform to explore all‐inorganic Sn‐based nanocrystalline thin films and optoelectronics.