Abstract
Bismuth telluride-based compounds are known to be the best thermoelectric materials within room temperature region, which exhibit potential applications in cooler or power generation. In this paper, thermal evaporation processes were adopted to fabricate the n-type Bi2Te3thin films on SiO2/Si substrates. The influence of thermal annealing on the microstructures and thermoelectric properties of Bi2Te3thin films was investigated in temperature range 100–250°C. The crystalline structures and morphologies were characterized by X-ray diffraction and field emission scanning electron microscope analyses. The Seebeck coefficients, electrical conductivity, and power factor were measured at room temperature. The experimental results showed that both the Seebeck coefficient and power factor were enhanced as the annealing temperature increased. When the annealing temperature increased to 250°C for 30 min, the Seebeck coefficient and power factor of n-type Bi2Te3-based thin films were found to be about −132.02 μV/K and 6.05 μW/cm·K2, respectively.
Highlights
Because the energy sources, such as petroleum, coal, and coal gas, will exhaust in the near future
The energy conversion efficiency of the thermoelectric materials is evaluated by the figure of merit ZT, ZT = (S2σ/κ)T (S, Seebeck coefficient; σ, electrical conductivity; T, absolute temperature; and κ, thermal conductivity) [3]
The power factor can be calculated according to the Seebeck coefficient and electrical conductivity
Summary
Because the energy sources, such as petroleum, coal, and coal gas, will exhaust in the near future. Thermoelectric (TE) effect is the simplest technology to convert the temperature difference to electrical energy. It generates electrical energy from the useless heat by thermoelectric effect. Thermoelectric materials can directly convert heat into electricity and vice versa They have a lot of important applications, such as power generator [1] and cooler [2]. The energy conversion efficiency of the thermoelectric materials is evaluated by the figure of merit ZT, ZT = (S2σ/κ)T (S, Seebeck coefficient; σ, electrical conductivity; T, absolute temperature; and κ, thermal conductivity) [3]. According to the formula, in order to obtain the excellent thermoelectric figure of merit, the materials must exhibit large Seebeck coefficient, high electrical conductivity, and low thermal conductivity. Because thermal annealing can affect the defect [17] and carrier concentration [18] of materials, it will influence the thermoelectric properties of the Bi2Te3 thin films
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