Perovskites are attractive for solar absorber materials, with extremely enhanced 22.1% of power conversion efficiency within 5 years. In theory, good solar absorbing materials also could be good light emitting materials, and in addition, the intrinsic property of narrow emission line width (~ 20nm) of perovskite material makes perovskite sas emerging materials for display application. But, the exciton binding energies of perovskite materials are quite low, so generated excitons are easily decomposed as free carriers, result in low PLQY.
In this study, we improved PLQY of perovskite materials by structural modification through controlling stoichiometry, and crystal size modification. In $FAPbBr_3$ films with FABr/$PbBr_2$ = 2 nonstoichiometric precursor solutions, we obtained 25% of PLQY by formation of Low-dimensional/3D heterojunction. For nanocrystal synthesis, we achieved 76.2% of PLQY in $CsPbBr_3$, and 29% in lead-free $Cs_3Sb_2Br_9$ nanocrystal.