Photoluminescence and Photoconductivity of Lead Halide Perovskite Films Modified with Mixed Cellulose Esters

We have investigated the photoluminescence (PL) and photoconductivity of lead halide perovskite (CH3NH3PbBr3) films modified with different mixed cellulose esters (CEs). It was shown that the absorbance and PL spectra of CH3NH3PbBr3:CE films contain contributions of both the CH3NH3PbBr3 and CE with the dominant contribution to the PL from perovskite component. The dependences of the integral PL intensities of the CH3NH3PbBr3:CE films on the optical excitation power turned out to be sublinear. This indicates that exciton recombination, as well as recombination via impurity levels, occurs in CH3NH3PbBr3:CE films at high excitation power levels. The conductivity of CH3NH3PbBr3:CE films at 300 K increases up to ~90 times when illuminated by a solar simulator, and this effect is environmentally stable due to the formation of hydrogen bonds between CE and the lead halide perovskite CH3NH3PbBr3. It is expected that appropriate selection of CE and optimization of CE inclusion will improve the optoelectronic properties and stability of composite films based on lead halide perovskite-CE composites.