Realizing high thermoelectric performance in n-type Bi2Te3 based thin films via post-selenization diffusion

Thermoelectric thin film has attracted a lot of attention due to its potential in fabricating micropower generator in chip sensors for internet of things (IoT). However, the undeveloped performance of n-type thermoelectric thin film limits its widely application. In this work, a facile post-selenization diffusion reaction method is employed to introduce Se into Bi2Te3 thin films, in order to optimize the carrier transport properties. Experimental and theoretical calculation results indicate that the carrier concentration decreases and density of states increases after Se doping, leading to the enhancement of Seebeck coefficient. Further, adjusting the diffusion reaction temperature can maintain the carrier concentration while increasing the mobility simultaneously, resulting in a high power factor of 1.5 mW/(m·K2), which is eight times higher than that of the pristine Bi2Te3 thin films. Subsequently, a thin film device fabricated by the present Se-doped Bi2Te3 thin films shows the highest output power of 60.20 nW under the temperature difference of 37 K, indicating its potential for practical use.