Microscale radiation in thermophotovoltaic devices - A review

Fast depleting reserves of conventional energy sources has resulted in an urgent need for increasing energy conversion efficiencies and recycling of waste heat. One of the potential candidates for fulfilling these requirements is thermophotovoltaic (TPV) devices. TPV devices generate electricity from either the complete combustion of different fuels or the waste heat of other energy sources, thereby saving energy. The thermal radiation from the emitter is incident on a TPV cell, which generates electrical currents. Applications of such devices range from hybrid electric vehicles to power sources for microelectronic systems. Absence of any moving parts and versatile fuel usage has made TPV devices very appealing for military and space applications. However, the presently available TPV systems suffer from low conversion efficiency. A viable solution to increase their efficiency is to apply microscale radiation principles in the design of different components to utilize the characteristics of thermal radiation at small distances and in microstructures. In order to have a clear understanding of microscale radiation and its role in TPV devices, several critical issues are reviewed in the present work. Emphasis is given to the development of wavelength-selective emitters and filters and the aspects of microscale heat transfer as applied to TPV systems. Recent progress, along with challenges and opportunities for future development of TPV systems are also outlined. Copyright (C) 2006 John Wiley & Sons, Ltd.