Ultra-Efficient Thermophotovoltaics Exploiting Spectral Filtering by the\n Photovoltaic Band-Edge

Thermophotovotaics convert thermal radiation from local heat sources to\nelectricity. A new breakthrough in creating highly efficient thin-film solar\ncells can potentially enable thermophotovoltaic systems with unprecedented high\nefficiency. The current 28.8% single-junction solar efficiency record, by Alta\nDevices, was achieved by recognizing that a good solar cell needs to reflect\ninfrared band-edge radiation at the back surface, to effectively recycle\ninfrared luminescent photons. The effort to reflect band-edge luminescence in\nsolar cells has serendipitously created the technology to reflect all infrared\nwavelengths, which can revolutionize thermophotovoltaics. We have never before\nhad such high back reflectivity for sub-bandgap radiation, permitting\nstep-function spectral control for the first time. Thus, contemporary\nefficiency advances in solar photovoltaic cells create the possibility of\nrealizing a $>50\\%$ efficient thermophotovoltaic system.\n