Organic thermoelectric devices with PEDOT:PSS/ZnO hybrid composites

Organic thermoelectric devices (OTEDs) are considered one of the most promising thermoelectric devices for harvesting electricity from low-temperature heat sources. Here it is demonstrated that the hybrid composites of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and zinc oxide (ZnO) particles enhance the performances of OTEDs due to the improved electrical conductivity by the bridging role of ZnO particles. The detailed study showed that the addition of ZnO particles to the aqueous solutions of PEDOT:PSS led to the increased viscosity owing to the specific interactions between sulfonic acid groups in PSS and hydroxyl groups (and/or zinc cations) in ZnO. The OTEDs with the PEDOT:PSS/ZnO hybrid composites with 70 wt% of 45 μm-sized ZnO particles exhibited 0.55 nW, which is ca. 7.8 times higher power than the devices with the pristine PEDOT:PSS sheets (0.07 nW). The wearable thermal sensors with the PEDOT:PSS/ZnO hybrid composite films showed fast thermoelectric responses toward heat and cool sources.