N-doped and Al-doped ZnO thin films as thermoelectric energy harvesters

Nitrogen-doped ZnO (P-type) and aluminum-doped ZnO (N-type) thin films were investigated for their thermoelectric properties. Under a temperature difference of 33.7K, N-doped ZnO was found to have higher ZT value of 0.697 and conversionefficiency (η) of 1.39% compared to Al-doped ZnO, which has a ZT value of 0.259 and η of 0.61%. These two materials can be coupled with each other in series to obtain higher ZT and η values that can be more efficient in harvesting energy in the form of waste heat. Moreover, N-doped ZnO showed to have a potential to work as a self-powered thermal sensor.