Unveiling the Ultralow Thermal Conductivity of Hybrid Perovskites

Hybrid perovskites are among the most important photon-to-electricity materials, whose performance is strongly limited by poor heat dissipation. This is due to their significantly low thermal conductivity, and the origin of such low thermal conductivity is still in debate and much less well-documented. In this paper, we experimentally observe that the thermal conductivity of hybrid perovskites is low and possesses a weak temperature dependence. We further show that this ultralow thermal conductivity of hybrid perovskites is caused by the disorder of organic molecules using atomistic simulations. This disorder strongly scatters the lattice vibrations and hinders the thermal transport in hybrid perovskites. Our calculations further show that the temperature dependence of the vibrational thermal conductivity results from the lattice framework transits from ∼T⁰ to ∼T^-1, and the value doubles at room-temperature and increases four-fold at 150 K when the disorder introduced by organic molecules is excluded. Meanwhile, based on atomistic simulations, the thermal energy in hybrid perovskites is found to be transferred by vibrations of the lattice framework (∼48% to ∼65%) and the organic molecules (∼35% to ∼52%). We map heat transport through inorganic octahedral cages and organic molecules, clarify their mutual coupling and interference, and guide thermal management in perovskites.