No abstract

The cesium lead bromide perovskite thin films prepared by chemical vapor deposition (CVD) have excellent optoelectronic properties， but the thin films generally have two different phase structures， CsPbBr 3 and CsPb 2 Br 5 . In our work， CVD method is considered to prepare cesium lead bromide perovskite thin films， and the effects of reaction pressure and N 2 flow on CsPb 2 Br 5 in the thin films were studied by X-ray diffraction (XRD)， scanning electron microscopy(SEM)， energy dispersive spectroscopy(EDS) and fluorescence spectrometer. The results show that the change of the reaction pressure has no effect on the CsPb 2 Br 5 phase. However， with the decrease of the N 2 flow， part of the CsPb 2 Br 5 phase in the film gradually transforms into the CsPbBr 3 phase， and its luminescence also converts from a broadband emission dominated by ~630 nm to a narrowband emission dominated by ~530 nm. Experimental results reveal that N 2 flow is an effective means to control the phase structure and luminescence properties of CsPb 2 Br 5 .Key words： chemical vapor deposition (CVD)； cesium lead bromide perovskite film； CsPb 2 Br 5 phase