Overcoming fundamental barriers in photovoltaic and terahertz generation
Several fundamental barriers limit the performance of opto-electronic conversion processes below 100%. Two specific examples of current technological interest include photovoltaic conversion of sunlight into electricity (i.e., solar cells), and terahertz generation from optical sources. In particular, solar cells are limited not only by the Carnot limit associated with the second law (approximately 86% at room temperature), but also by radiative recombination, non-reciprocity, carrier thermalization, and sub-bandgap losses. In the case of terahertz generation, the typical process of difference frequency generation relies on two input optical waves with only a small difference between them to generate the desired output; however, this process has efficiency sharply constrained by the frequency ratios, known as the Manley-Rowe relations. Numerous researchers have recently examined a range of methods for overcoming these barriers and enabling new applications. However, given the large number of possible methods and functional parameters, it is best to avoid an Edisonian approach and develop detailed physics-based models of the optical and electrical performance of these systems capable of accurately predicting their performance. Combining analytical techniques with the recent exponential rise in computing power available through Moore's law allows for a targeted search that could enable new discoveries in future experiments.
Bermel, Purdue University.
Alternative Energy|Electrical engineering|Electromagnetics|Energy
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