A Highly Conductive Conjugated Polyelectrolyte for Flexible Organic Thermoelectrics
Seyoung Kee, Md Azimul Haque, Yeran Lee, Thanh Luan Nguyen, Diego Rosas Villalva, Joel Troughton, Abdul‐Hamid Emwas, Husam N. Alshareef, Han Young Woo, Derya Baran
Abstract
Organic thermoelectrics have attracted considerable attention owing to their remarkable advantages, including room-temperature power generation, skin-attachable/wearable applications with biocompatibility, and solution-based high-throughput fabrication. Self-doped conjugated polyelectrolytes (CPEs) constitute a promising class of conductive organic materials that are considered potential candidates for organic thermoelectrics. However, the low power factor of CPEs derived from their low electrical conductivity (σ) has been a major drawback in CPE-based thermoelectrics. Herein, we report a strategy for enhancing the thermoelectric performance of CPEs through post-treatment using aq H2SO4 solution. The post-treatment increases σ by 2 orders of magnitude, originating from H2SO4-induced doping accompanying a significant increase in charge-carrier concentration. Consequently, a power factor of 3.0 μW m–1 K–2 is achieved at room temperature. Furthermore, using this highly conductive H2SO4-doped CPE, we developed flexible thermoelectric generators that allow durable power generation under repetitive mechanical bending stresses. Our findings provide insight into developing high-performance and versatile CPEs for the next-generation organic thermoelectrics.