One-Pot Synthesis\nof High-Quality CsPbI<sub>3</sub> Nanoplatelets with Orange-Red Light\nEmission

CsPbI<sub>3</sub> nanoplatelets (NPLs) are considered\npotential\ncandidates for orange-red light-emitting materials due to their high\nexciton binding energy and narrow full width at half maximum (FWHM).\nHowever, the relatively low formation energy of CsPbI<sub>3</sub> NPLs\nleads to rapid growth rates, posing a challenge for the controlled\nsynthesis of high-quality CsPbI<sub>3</sub> NPLs. Herein, we report\nthe synthesis of high-quality CsPbI<sub>3</sub> NPLs emitting orange-red\nlight using a one-pot method under mild reaction conditions. The protonation\nof oleylamine (OAm) by introducing HI and the strong interaction between\nthe octadecylphosphonic acid (ODPA) ligand and Pb<sup>2+</sup> facilitate\nthe anisotropic growth of CsPbI<sub>3</sub> NPLs and enable precise\ncontrol over the numbers of NPL layers, achieving the desired orange-red\nlight emission. The resulting CsPbI<sub>3</sub> NPLs exhibited a high\nphotoluminescence quantum yield (PLQY) of up to 90%, a narrow FWHM\nof only 25 nm, and excellent stability at room temperature, under\nultraviolet–visible light and in aqueous environments. The\ncomprehensive study of the formation process of CsPbI<sub>3</sub> NPLs\nenriches our understanding of the growth mechanism and provides a\nsynthetic route for producing high-quality CsPbI<sub>3</sub> NPLs.