Thermoelectric Properties of Co-doped ZnO by Incorporating Organic Nanoparticles

Organic-inorganic nanojunction can result in a selective scattering of charge carrier depending on their energy, which leads to a simultaneous increase in Seebeck coefficient S and power factor PF when the Fermi levels of the constituent materials are aligned appropriately. In this work, the nanojunction was employed at the organic-inorganic semiconductor interface of polyparaphenylene (PPP) and Zn1-xCoxO nanoparticles through a sol-gel method. The resulting Zn0.925Co0.075O/9wt% PPP hybrids exhibit a high power factor due to the largest electrical conductivity and higher Seebeck coefficient. Moreover, organic-inorganic nano-interface effectively reduces the thermal conductivity by interface scattering of phonons. All these effects finally lead to a thermoelectric figure of merit, ZT up to 0.22 in these inorganic-organic nanocomposites, which corresponds to a 5-fold enhancement compared to that of the Zn0.925Co0.075O matrix. This work demonstrates the effectiveness of nanojunctions and provides a rational route to high performance thermoelectrics in a bulk material.