Water mediated synthesis of phase-stable red-emitting CsPbI3 nanocrystals

With the unusual luminescence and photoconductive characteristics, the CsPbI3 perovskite has attracted a lot of attention in the field of material synthesis and device fabrication. The general synthesis methods of CsPbI3 are through the organic solvent spin-coating and heating. To avoid the toxic organic solvent, herein we reported the organic solvent-free synthesis method. The precursors PbI2 and CsI were solved in aqueous solution and heated to form the CsPbI3 perovskite. It is found that the Na2S2O3 as a reaction additive could enhance the CsPbI3 crystal quality and the synthesis temperature could be lowered down to 80 °C. The content of Pb2+ was increased by combination with S2O32− in Na2S2O3 aqueous solution. The photoluminescence (PL) spectra showed the PL of CsPbI3 perovskite can disappear/recover through absorbing/removing to moisture, respectively. By integrating the CsPbI3 film to the blue diode, we obtained an LED device. Our method provides an innovative strategy to prepare CsPbI3 perovskites in aqueous solution. We reported water mediated synthesis of phase-stable red-emitting CsPbI3 nanocrystals at the reaction temperature as low as 80 °C with the introduced Na2S2O3 additive. The photoluminescence (PL) spectra with could be fully recovered after continuous cycles of moisture absorption and removal. The temperature-dependence PL spectra demonstrated that the CsPbI3 prepared in the presence of Na2S2O3 exhibited the better PL properties and crystal quality compared with that in the absence of Na2S2O3.