New thermoelectric materials and applications

New and more-efficient nanostructuted thermoelectric materials have been developed. These new materials, called quantum wells (QW), are composed of alternating layers of 10 nm thick silicon and SiGe films, and with such confinement all of the thermoelectric properties are improved to increase the thermoelectric Figure of Merit, ZT. Room-temperature ZTs greater than 3 were obtained for QW materials, which constitutes a significant improvement over state-of-the-art (SOTA) bulk thermoelectrics which have ZTs less than 1. QW ZTs greater than 3 lead to conversion efficiencies greater than 20% for QW materials which allows for much wider commercial applications, particularly in applications such as the waste-heat recovery from truck engines, refrigeration, and air conditioning, where SOTA bulk thermoelectric modules were shown to be technically feasible but economically unviable due to low conversion efficiencies. For refrigeration and air conditioning applications, QW thermoelectric materials are predicted to have higher coefficients of performance (COP) than SOTA vapor-compression systems, with the additional advantages of having no compressors, moving parts, refrigerants, vibrations, noise, and practically no maintenance. The temperature range for applications is anticipated to be from -150C to 1000C, with power generation capacity ranging from milliwatts to kilowatts and cooling capacity ranging from watts to several tons of refrigeration.