Excitonic optical properties of cesium trifluoroacetate induced CsPbBr3 thin film with anti-solvent treatment

In this paper, the cesium trifluoroacetate induced CsPbBr3 thin film with anti-solvent chlorobenzene treatment was fabricated where the anti-solvent treatment improved CsPbBr3 photoluminescence emission intensity, thin film surface morphology and crystallization quality. Temperature-dependent photoluminescence and time-resolved photoluminescence from the CsPbBr3 thin film were measured from 10 K to room temperature. Free exciton and bound exciton recombination photoluminescence was identified. The photoluminescence intensity of CsPbBr3 thin film demonstrated a bi-exponentially quenching process with the increase of temperature, yielding two activation energies of 45.54 meV and 9.06 meV for high and low temperature. The photoluminescence lifetime of the CsPbBr3 thin film increased as temperature changed from 20 K to 300 K due to the dissociation effect of excitons. The transient photoluminescence spectra showed an unusual PL peak reverse due to the exciton-exciton scattering and Burstein-Moss effect, which was further observed in the transient absorption spectra. Our results confirm the unique exciton emission profile of the cesium trifluoroacetate induced CsPbBr3 thin film and reveal the complex carriers dynamics property using transient spectroscopy method.