Residue‐Free Liquid‐Crystal Molecular Additive Enables the Significant Improvement of Power Factor for Simple Quinoid Thermoelectric Polymer

Abstract Quinoid polymers featured with high‐spin ground states hold great potential for applications in organic thermoelectrics (OTE) since the radicals are liable to regulate the molecular electronic structure and carrier transfer ability. Whereas, only a few fused quinoid polymers are explored with low power factor (PF) currently. Herein, a liquid‐crystal molecule‐assisted strategy is proposed to promote a PF breakthrough of quinoid polymers. By introducing liquid‐crystal molecule 5CB into the simple non‐fused quinoidal polymer PAQM‐3T which exhibits stable high‐spin characters, a tighter molecular assembly can be readily induced without any residue upon thermal annealing, leading to nearly doubled carrier mobility and conductivity. Moreover, 5CB‐treatment causes few impacts on the high‐spin character and the Seebeck coefficient (S) can keep a high value under heavy p‐type doping conditions. Ultimately, the optimal PF of PAQM‐3T reaches 198.4 µW•m −1 •K −2 , higher than those of the traditional simple non‐fused aromatic polymers. Notably, 10% wt 5CB‐treated film boosts the PF up to 309.55 µW•m −1 •K −2 with enhanced conductivity of 145.27 S•cm −1 and well‐balanced S of 146.6 µV•K −1 , which is the highest value among quinoid materials and even approaching to those of the state‐of‐the‐art aromatic polymers. The breakthrough efficiency highlights the promising prospect of liquid‐crystal molecular‐assisted simple quinoid polymers for high‐performance OTE.