Abstract
Thermoelectric technology can achieve mutual conversion between thermoelectricity and has the unique advantages of quiet operation, zero emissions and long life, all of which can help overcome the energy crisis. However, the large-scale application of thermoelectric technology is limited by its lower thermoelectric performance factor (ZT). The thermoelectric performance factor is a function of the Seebeck coefficient, electrical conductivity, thermal conductivity and absolute temperature. Since these parameters are interdependent, increasing the ZT value has always been a challenge. Here, we report the growth of Cu2Se thin films with a thickness of around 100 nm by magnetron sputtering. XRD and TEM analysis shows that the film is low-temperature α-Cu2Se, XPS analysis shows that about 10% of the film’s surface is oxidized, and the ratio of copper to selenium is 2.26:1. In the range of 300–400 K, the maximum conductivity of the film is 4.55 × 105 S m−1, which is the maximum value reached by the current Cu2Se film. The corresponding Seebeck coefficient is between 15 and 30 µV K−1, and the maximum ZT value is 0.073. This work systematically studies the characterization of thin films and the measurement of thermoelectric properties and lays the foundation for further research on nano-thin-film thermoelectrics.
Highlights
The global energy crisis and environmental problems caused by the burning of fossil fuels have aroused widespread concern about alternative energy sources
AFM measurement found that the surface of the film was rough, indicating that the prepared nanofilm introduced nanostructures with different length scales, which may effectively scatter in the entire phonon spectrum, thereby reducing the thermal conductivity of the material
The thermal conductivity of the film grown at different substrate temperatures at room temperature was measured at about 2 W m−1 K−1, which was equivalent to the thermal conductivity measured by Byeon et al [19]
Summary
The global energy crisis and environmental problems caused by the burning of fossil fuels have aroused widespread concern about alternative energy sources. Thermoelectric (TE) materials can directly convert industrial waste heat into useful electrical energy only through solid-state methods. They can be used as heat pumps to provide local cooling. They have many advantages, such as lightweight, reliability, complete solid-state, and long service life, the use of TE materials is limited mainly due to low conversion efficiency. Extensive research has been conducted to improve the thermoelectric efficiency, which is evaluated by the dimensionless quality factor ZT (ZT = S2 σT/κ), where σ is the conductivity, S is the Seebeck coefficient, T is the absolute temperature, and κ is the total thermal conductivity, including the contribution of its electronic (κ e ) and lattice (κ L ) components. Due to the interdependence and conflict of Seebeck coefficient, electrical conductivity and thermal conductivity, how to optimize the various parameters of S, σ and κ is always a challenge
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