An Overview of Meta-Level Architecture

Abstract

Hybrid organic-inorganic perovskites have emerged as promising thermoelectric materials due to their attractive figure of merits. To further reduce their thermal conductances (<i>G</i>) and improve the thermoelectric efficiencies, fabrication of phononic crystals (PnCs) could be an effective approach. In this work, CH₃NH₃PbI₃-based PnCs were developed and their thermal transports were engineered by optimizing the configurations of both basal bodies and scatterers. Our cross-scale simulations demonstrate that low relative <i>G</i> can be achieved in CH₃NH₃PbI₃ PnCs with large scatterers but low-symmetric PnC lattices, basal bodies, and scatterers. Moreover, we discovered the increased disorder of CH₃NH₃⁺ cations from tetragonal to cubic transition significantly increases the phonon velocities and reverses the phonon transport from diffusive to quasi-ballistic, leading to an abnormal reduction of relative <i>G</i>. This work provides a new pathway for engineering thermal conductivity of hybrid perovskites and improving the performance of corresponding devices.