Waste heat recovery systems in vehicles: A large number of car companies, including Volkswagen, VOLVO, FORD and BMW in collaboration with NASA have been developing thermoelectric waste heat recovery systems in-house, each achieving different types of performance but all of them expecting to lead to improvements of 3-5% in fuel economy while the power generated out of these devices could potentially reach up to 1200W. What does the future hold with electrification of vehicles globally picking up pace and the market conditions turning unfavorable for thermoelectrics that require the high temperatures present in internal combustion engines for optimal operation.  

Wireless sensor network adoption: Wireless sensors powered by thermogenerators in environments where temperature differentials exist would lead to avoiding issues with battery lifetime and reliability. It would also lead to the ability to move away from wired sensors, which are still the solution of choice when increased reliability of measurement is necessary. Some applications have low enough power demands to operate with small temperature differentials, as small as a few degrees in some cases. These types of developments increase adoption trends.  

Consumer applications: In these applications, the type of solution that thermogenerators provide varies: it could be related to saving energy when cooking by utilising thermo-powered cooking sensors, powering mobile phones, watches or other consumer electronics, even body sensing could become more widespread with wearables such as sensory wristbands, clothing or athletic apparel that monitor vitals such as heart rate, body temperature, etc.

Hi jeetendra

I attached a useful power point presentation it starts from basic principles to advanced knowledge you can start your research based on it. You need also to read about semiconductors and heat transfer

Look at thermionic emission. Thermionic uses 100% if the light spectrum, much better than silicon or any other semiconductor, but you should use lenses or mirrors to concentrate light power.

One of the lowest work function compounds is cesium.