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 (CH$_{3}$NH$_{3}$PbBr$_{3}$) films modified with different mixed cellulose esters (CEs). It was shown that the absorbance and PL spectra of CH$_{3}$NH$_{3}$PbBr$_{3}$ : CE films contain contributions of both the CH$_{3}$NH$_{3}$PbBr$_{3}$ and CE with the dominant contribution to the PL from perovskite component. The dependences of the integral PL intensities of the CH$_{3}$NH$_{3}$PbBr$_{3}$ : CE films on the optical excitation power turned out to be sublinear. This indicates that exciton recombination, as well as recombination via impurity levels, occur in CH$_{3}$NH$_{3}$PbBr$_{3}$ : CE films at high excitation power levels. The conductivity of CH$_{3}$NH$_{3}$PbBr$_{3}$ : CE films at 300 K increases up to $\sim$ 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 CH$_{3}$NH$_{3}$PbBr$_{3}$. 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.