摘要
Fast and efficient ion-exchange reactions endow CsPbX 3 nanocrystals (NCs) with superior photoluminescence (PL) properties. In this study, SnX 2 (X = I, Cl) was used as a Sn precursor to conduct the cation exchange reaction, which was promoted by anion exchange between the parent CsPbBr 3 NCs and the guest X in SnX 2 . The anion-driven cation exchange reaction occurred efficiently (10 min). CsSnI 3 NCs were created by ion-exchange reactions between CsPbBr 3 NCs and the SnI 2 precursor. The CsSnI 3 NCs retained the initial morphology of CsPbBr 3 NCs and revealed a high PL efficiency (59%) and prolonged PL lifetime. In contrast, the exchange reaction of Sn 2+ ions in CsPbBr 3 NCs did not occur in a short time using SnBr 2 as a precursor. After the cation exchange reaction, the 4f peaks of Pb ions in X-ray photoelectron spectroscopy spectra shifted to low binding energies as compared to those of the parent CsPbX 3 NCs. This is ascribed to the increase in the number of Pb-oleate (Pb-OA) species. Contrary to the hot-injection method used to synthesize CsSnI 3 NCs, the kinetically controlled ion exchange reactions lead to the synthesis of CsSnI 3 NCs with a high structural stability. Thus, an anion-exchange-promoted cation exchange reaction is a particularly efficient versatile tool to dope Sn 2+ into CsPbX 3 NCs.