Effect of incorporation of PbS nanocrystals on optical properties of the hybrid organic-inorganic MAPbI3 perovskite

Abstract

Solution-processed PbS quantum dots embedded into organic–Inorganic lead hybrid Halide Perovskites have been synthesized and analyzed by photoluminescence, optical absorption, X-ray diffraction and scanning electron microscopy techniques. The PL at 10 and 77 K showed that both the orthorhombic and tetragonal phases are present in MAPbI3 and MAPbI3/PbS films. At 300 K, PL spectra and X-ray diffractions show only the tetragonal phase in the systems, and SEM images show that as the PbS quantum dots concentration increases the size of the MAPbI3/PbS grain is reduced, showing that perovskite nucleation is affected. PL spectra as a function of excitation intensity, at room-temperature, reveled an additional thin and intensity emission at lower energy side in relation to excitonic emission of the perovskite. This thin emission appears at high excitation intensities, and it is intensified with increasing of the PbS quantum dots concentration. The integrated emission as function of excitation intensity presents a characteristic low-threshold behavior associated with the exciton−polariton effect in the perovskite hybrid MAPbI3/PbS thin films.