Thermophotovoltaic Energy Conversion in Far-to-Near-Field Transition Regime
Jaeman Song, Junho Jang, Mikyung Lim, Minwoo Choi, Jungchul Lee, Bong Jae Lee
Abstract
Recent experimental studies on near-field thermophotovoltaic energy conversion have mainly focused on improving performance via photon tunneling of evanescent waves. In the sub-micron gap, however, there exist peculiar phenomena induced by the interference of propagating waves, which are seldom observed in the full spectrum radiation due to the massive increase in evanescent modes. Here, we experimentally demonstrate the oscillatory nature of near-field thermophotovoltaic energy conversion in the far-to-near-field transition regime (250–2600 nm), where evanescent and propagating modes are comparable due to the selective spectral response by the photovoltaic cell. Noticeably, we show that the same amount of photocurrent can be generated at different vacuum gaps of 870 and 322 nm, which is 10% larger than the far-field value.