Complex Dependence of Optoelectronic Properties of Metal Halide Perovskite Thin Films on Quantum Dot Decoration Layers

The interaction between CH3NH3PbI3 (methylammonium lead iodide or MAPI) thin films and metal halide perovskite quantum dots (PQDs) was studied using spectroscopic techniques. By comparing PQDs with Cs+ and CH3NH3+ cations and different surface passivation, including both conducting and insulating molecular ligands, charge transfer interactions between the PQDs and the MAPI films were tuned. Mapping static and dynamic MAPI emission as functions of temperature, excitation wavelength, and excitation power revealed that a low density of PQDs improved MAPI photoluminescence (PL) properties, including increased intensity and average recombination lifetime. However, a high density of PQDs had detrimental effects, resulting in a spectral blue shift of MAPI emission and a shortening of charge carrier lifetimes. This complex modulation of MAPI properties by PQDs indicates an intricate interplay between different factors that need to be considered in optimizing such heterostructures for optoelectronic applications.