TRAP (Thermo-Radiative Assisted Photovoltaic) Cell to Simultaneously Harvest Incoming Solar and Outgoing Thermal Radiation

Advanced Cooling Technologies, Inc. (ACT) proposes to develop a TRAP (Thermo-Radiative Assisted Photovoltaic) Cell technology to simultaneously harvest the incoming solar and outgoing thermal radiation in a single integrated device, with goals to achieve total efficiency gt;35% in the near-term (~2 years) and gt; 45% in the mid- to far-term (5-10 years). ACTrsquo;s TRAP Cell leverages the ldquo;darkrdquo; photovoltaic (i.e., thermo-radiative (TR) cell) technology that ACT has developed in two previous successful NASA SBIR programs. A TR cell can be viewed as the reverse mode of a PV cell. In a PV cell, the electrical power generation can be viewed as a result of the imbalance of incoming radiation from the sun and outgoing radiation from the PV cell. Conversely, the electrical power generation in the TR cell is a result of imbalance of the outgoing thermal radiation and negligible incoming radiation (from deep space), which creates a charge carrier motion resulting in electric power generation. Our proposed TRAP Cell will consist of three layers: a conventional space photovoltaic cell as the top layer, a mid-infrared transparent solar absorber as the middle layer, and a ldquo;darkrdquo; photovoltaic cell as the bottom layer. When producing electrical power, the conventional PV cell needs to face the sun, while the ldquo;darkrdquo; photovoltaic cell needs to face the ultra-cold deep space. To address the challenges when combining them together, we introduce a mid-infrared transparent solar absorber layer (e.g., undoped germanium layer) between the solar cell and the ldquo;darkrdquo; photovoltaic cell. Due to the mid-infrared transparent nature of the solar cell (top layer) and solar absorber (middle layer), the bottom thermo-radiative cell layer is only radiatively coupled to the ultra-cold deep space, while the top and middle layers will utilize the entire solar spectrum by either generating electricity directly or converting unused solar radiation into heat to provide thermal energy for the bottom layer