Ligand-mediated evolution from CsPbBr3 to Cs4PbBr6/CsPbBr3 perovskite composites with intense green emission

Herein, CsPbBr 3 and Cs 4 PbBr 6 /CsPbBr 3 perovskite composites have been synthesized by a simple supersaturated recrystallization procedure. X-ray diffraction and absorption spectra confirm the evolution from CsPbBr 3 to Cs 4 PbBr 6 by adding oleic acid and oleylamine simultaneously, which leads to the formation of green emissive Cs 4 PbBr 6 /CsPbBr 3 perovskite composites. Gaussian fitting of the emission spectra and luminescent lifetime investigation indicate that the green emission is attributed to both Cs 4 PbBr 6 and CsPbBr 3 , which originates from the exciton radiative recombination mediated by the trap states and the electron-hole recombination, respectively. Moreover, the emissive Cs 4 PbBr 6 can further promote the emission of CsPbBr 3 by energy transfer process in Cs 4 PbBr 6 /CsPbBr 3 composites. The photoluminescence intensity declines by less than 10 % after 60 days of storage in ambient environment, reflecting the excellent stability of the composites for lighting and displaying application.