Enhancing zT in Organic Thermoelectric Materials through Nanoscale Local Control Crystallization

Organic thermoelectric materials are promisingfor wearable heating and cooling devices, as well as near-room-temperature energy generation, due to their nontoxicity,abundance, low cost, and flexibility. However, their primarychallenge preventing widespread use is their reduced figure ofmerit (zT) caused by low electrical conductivity. This studypresents a method to enhance the thermoelectric performanceof solution-processable organic materials through confinedcrystallization using the lithographically controlled wetting(LCW) technique. Using PEDOT as a benchmark, wedemonstrate that controlled crystallization at the nanoscaleimproves electrical conductivity by optimizing chain packingand grain morphology. Structural characterizations reveal the formation of a highly compact PEDOT arrangement, achievedthrough a combination of confined crystallization and DMSO post-treatment, leading to a 4-fold increase in the power factorcompared to spin-coated films. This approach also reduces the thermal conductivity dependence on electrical conductivity,improving the zT by up to 260%. The LCW technique, compatible with large-area and flexible substrates, offers a simple,green, and low-cost method to boost the performance of organic thermoelectrics, advancing the potential for sustainableenergy solutions and advanced organic electronic devices