Nanoscale Decoupling of Carrier–Phonon Transport in Carbon Nanotube–Halide Perovskite Heterostructures

In conventional semiconductors, electrical and thermal conductivity are typically coupled, posing a challenge in optimizing both simultaneously. Overcoming this inherent trade‐off enables strategies for advancing electronic applications. Herein, a strategy is demonstrated to decouple electrical and thermal conductivity trade‐off by creating heterostructures of highly conductive single‐walled carbon nanotubes (SWCNTs) coated with low conductivity hybrid perovskites. Coating SWCNTs with methylammonium lead iodide perovskite results in an enhancement in electrical conductivity (408–1266 S cm −1 ) due to p‐type doping followed by a threefold decrease of the in‐plane thermal conductivity (3.3–1 W m −1 K −1 ), compared to pristine SWCNTs. Molecular dynamics simulations uncover phonon boundary scattering at the SWCNT/perovskite interface as well as localization of methylammonium‐related and softening of the Pb─I‐related phonon modes in methylammonium lead iodide perovskite decreasing the thermal conductivity.