A solar cell is an electronic device which directly converts sunlight into electricity. Light shining on the solar cell produces both a current and a voltage to generate electric power. This process requires firstly, a material in which the absorption of light raises an electron to a higher energy state, and secondly, the movement of this higher energy electron from the solar cell into an external circuit. The electron then dissipates its energy in the external circuit and returns to the solar cell. A variety of materials and processes can potentially satisfy the requirements for photovoltaic energy conversion, but in practice nearly all.
Thermoelectric power generation is based on seebeck effect that was discovered in 1821. From the temperature difference of hot and cold side, we can harvest the electrical energy. To enhance the efficiency of thermoelectric generator, there are two key factors, which is temperature difference (ΔT) and dimensionless figure of merit (ZT). Temperature difference ΔT is system factor of thermoelectric generator that drives the charge carriers from hot side to cold side. Dimensionless figure of merit (ZT) is materials’s intrinsic properties that consists of three parameters (electrical conductivity, seebeck coefficient, thermal conductivity)
Water electrolysis is a viable technology to decompose water into chemical fuels, especially hydrogen, either using electricity (potential) or solar light which can be efficiently used in a fuel cell for power generation. Based on this technology, hydrogen is now considered as a green energy carrier. However, to generate hydrogen, some key factors must be addressed: properly choosing the materials for catalytic activity, designing the catalysts, and engineering the water-splitting devices.