Organic/polymeric materials are potential candidates for next-generation highperformance thermoelectric materials because of their remarkable low thermal conductivity, relatively high electrical conductivity by doping, structural flexibility, light weight, low toxicity, and biocompatibility . Past decades witnessed rapid development in the field and a number of promising organic/polymeric thermoelectric materials have been synthesized, varying from small molecular systems to conducting polymers . However, organic materials' thermoelectric figure of merit ZT is still low compared to the inorganic counterpart, mainly because of the low power factor (PF). Theoretical understandings are essential for the development of novel highperformance thermoelectric materials. First-principle band structure calculations have been pivotal in such cases. Band structure theory assumes that both electron correlation and electron-phonon coupling are weak and thus the electrons are delocalized.