Thermal Conductivity of Methylammonium Lead Halide Perovskite Single Crystals and Thin Films: A Comparative Study

Thermal management in devices like solar cells, light-emitting diodes, and lasers based on hybrid halide perovskite thin films is expected to be of paramount importance for optimal performance and reliability. As of yet, experimental data of thermal properties of non-iodine-based hybrid halide perovskites is very scarce. Here the thermal conductivity of methylammonium lead halide perovskite (CH₃NH₃PbX₃ X= I, Br, and Cl) single crystals and thin films is analyzed by scanning near-field thermal microscopy. The thermal conductivity of CH₃NH₃PbX₃ single crystals with X= I, Br, and Cl is found to be 0.34 ± 0.12, 0.44 ± 0.08, and 0.50 ± 0.05 W/(mK) at room temperature, respectively. Strikingly, similar thermal conductivities are determined for the corresponding thin-film samples. The thermal conductivity of MAPbI₃ in the cubic phase (<i>T</i> > 55 °C) increases to (1.1 ± 0.1) W/(mK). In addition, the temperature dependence of the thermal conductivities and of thermal expansion coefficients of MAPbI₃ around the phase transition from the tetragonal to cubic phase is presented