Effect of low-dimensional carbon composite on the thermoelectric properties of vacuum evaporated ZnO: Al films

The low-dimensional carbon composite is expected to improve electrical conductivity and reduce the thermal conductivity of thermoelectric (TE) materials, which is considered an effective method to improve the TE properties of materials. However, the different dimensions of carbon have various effects on the properties of TE film composite. This study investigated the effects of zero-dimensional fullerene, one-dimensional carbon nanotubes (CNT), and two-dimensional graphene on the TE properties of vacuum evaporated ZnO: Al films. The results demonstrated that these three types of composites influenced the carrier concentration and mobility of the films, which in turn affected the TE properties and output power. The lower the dimension of carbon, the higher the carrier concentration of the film. The CNT composite did not affect the microstructure and preferred orientation. However, it increased the particle size and surface roughness. The interface between CNT and ZnO: Al provided more carriers and improved effective mass, thereby increasing the Seebeck coefficient. In addition, the CNT can be used as a carrier transport channel to improve carrier mobility because of its unique tubular structure. Therefore, the CNT composited ZnO: Al films demonstrated the best TE performance and output power. Its power factor reached 136.5 mu K--1(-2) at room temperature.

Automated summary

The low-dimensional carbon composite is expected to improve the electrical conductivity and reduce the thermal conductivity of thermoelectric materials. This study investigated the effects of different dimensions of carbon (fullerene, carbon nanotubes, and graphene) on the thermoelectric properties of ZnO:Al films. The results showed that the lower the dimension of carbon, the higher the carrier concentration, and the better the thermoelectric performance. Among the three composites, the carbon nanotube composite exhibited the best thermoelectric performance with a power factor of 136.5 mu K-1(-2) at room temperature.