Physical mechanism on ladderphane copolymers with electron localization and phonon delocalization for capacitive energy storage

In this article, the properties of trapezoidal polymer PSBNP-co-PTNI for capacitive energy storage are investigated theoretically, stimulated by the recent experimental reports [Chen et al., Nature 615, 62 (2023)]. The flatband structures of PSBNP-co-PTNI copolymer reveal that very large effective mass of electron results in Anderson electron localization and then small electric conductance. The TNI doping significantly decreases optical absorption in an ultraviolet region, which can significantly suppress photocurrent. Raman spectrum demonstrates that phonon Debye temperature can be significantly decreased, due to the U-process of phonon scattering by TNI doping, and then results in the phonon delocalization, and then the large thermal conductivity and thermal capacity. The simultaneous regulations on decreasing electric conductivity and on increasing thermal conductivity can significantly increase the ability of capacitive energy storage. The unit-length dependent thermal electric current manifests that the thermal electric current can be significantly decreased by slightly increase in length of copolymer. Overall, our research contributes to the understanding of the impact of TNI doping on the energy storage properties of the polymer and provides a valuable reference for future research focused on polymer energy storage.