Cation Dynamics Governed Thermal Properties of Lead Halide Perovskite Nanowires.

Metal halide perovskite (MHP) nanowires such as hybrid organic-inorganic CHNHPbX (X = Cl, Br, I) have drawn significant attention as promising building blocks for high-performance solar cells, light-emitting devices, and semiconductor lasers. However, the physics of thermal transport in MHP nanowires is still elusive even though it is highly relevant to the device thermal stability and optoelectronic performance. Through combined experimental measurements and theoretical analyses, here we disclose the underlying mechanisms governing thermal transport in three different kinds of lead halide perovskite nanowires (CHNHPbI, CHNHPbBr and CsPbBr). It is shown that the thermal conductivity of CHNHPbBr nanowires is significantly suppressed as compared to that of CsPbBr nanowires, which is attributed to the cation dynamic disorder. Furthermore, we observed different temperature-dependent thermal conductivities of hybrid perovskites CHNHPbBr and CHNHPbI, which can be attributed to accelerated cation dynamics in CHNHPbBr at low temperature and the combined effects of lower phonon group velocity and higher Umklapp scattering rate in CHNHPbI at high temperature. These data and understanding should shed light on the design of high-performance MHP based thermal and optoelectronic devices.