Backbone Asymmetry Modification in Amphipathic Conjugated Polymers Enables Record n‐Type Organic Thermoelectrics

Abstract

Abstract Achieving high‐performance n‐type organic thermoelectrics (OTEs) has lagged behind p‐type counterparts due to limited electrical conductivity and power factor (PF). Here, we report two n‐type amphipathic conjugated polymers, Pg 5 DPP‐BBTz and Pg 5 DPP‐TBZ, based on glycolated thiophene‐diketopyrrolopyrrole units, engineered via backbone modification to enhance charge transport. Replacing a symmetric sp 2 ‐sulfur atom in Pg 5 DPP‐BBTz with an sp 2 ‐nitrogen atom yields the asymmetric Pg 5 DPP‐TBZ, which exhibits stronger π–π stacking, a more favorable density of states distribution, and extended charge delocalization. When sequentially doped with N‐DMBI, Pg 5 DPP‐TBZ achieves an electrical conductivity of 145.6 ± 1.5 S cm −1  and a record‐high PF of 385 ± 16 µW m −1 K −2 —surpassing previous n‐type OTEs and rivalling top p‐type materials. This performance stems from high charge mobility, large delocalization, and mitigated carrier‐carrier repulsion. Combined with a low thermal conductivity (0.37 W m −1 K −1 ), a ZT of 0.30 ± 0.02 is realized. Our work demonstrates that subtle backbone modification in amphipathic polymers is a powerful strategy to advance n‐type thermoelectrics.