Recombination Dynamics of Chlorine Doped Hybrid Perovskite Single Crystals

Controlling the photo excited properties and behavior of hybrid perovskites by halide doping has the potential to impact a wide range of emerging technologies, including solar cells and radiation detectors. Crystalline samples of methyl ammonium lead bromide (MAPbBr) were substituted with varying levels of Cl at the c site and probed with transient reflectivity spectroscopy. MAPbBr perovskites exhibit an increase in transient reflectivity following photoexcitation, with electron-phonon relaxation on a few picosecond timescale and a triple exponential recombination dynamic which is not complete after 1.5 nanoseconds. The recombination dynamics strongly depend on pump fluences, while the electron-phonon relaxation remains unchanged. We also observed that the doping level affected the electron-phonon coupling within the conduction band, becoming stronger with increased percentage of Cl.