Innovators at NASA’s Glenn Research Center have developed a low-cost, high-efficiency solar cell that uses a thin layer of selenium as the bonding material between wafers. Selenium is a semiconductor, and it is also transparent to light at photon energies below the band gap. The innovation allows a multi-junction solar cell to be developed without the constraint of lattice matching, and uses a low-cost, robust silicon wafer as the supporting bottom substrate and bottom cell. This enables a cell that is simultaneously lower in cost, more rugged, and more efficient than existing space solar cell designs. This technology has the potential to be used in next-generation solar cells in space, and it can be commercialized for terrestrial applications such as power plants and smart grid systems.
This innovation is a novel method for manufacturing a multi-junction photovoltaic (PV) cell using selenium as a bonding material sandwiched between two multi-junction wafers, enabling higher efficiencies. A multi-junction PV cell differs from a single junction cell in that it has multiple sub-cells (p-n junctions). A multi-junction cell can convert more of the Sun’s energy into electricity as the light passes through each layer. Glenn Research Center’s multi-junction PV cell has three junctions to improve efficiencies further, where the top wafer is comprised of high solar-energy absorbing materials forming a two-junction cell, and the bottom wafer would remain a simple silicon wafer substrate. The three-junction solar cell manufactured using selenium as the transparent interlayer has a higher efficiency than traditional multi-junction cells.
The technology has a 40% expected conversion efficiency. PV cells can be manufactured on a large scale, and have a low environmental impact (zero greenhouse gasses emitted). In addition, the rugged design can be used for both space and terrestrial applications.
This is an early-stage technology requiring additional development. Glenn welcomes co-development opportunities. Potential applications include utility-scale PV power plants, PV distributed generation (PV-DG) for smart grid systems, building-integrated photovoltaics (BIPV), building-applied photovoltaics (BAPV), government communications systems, military and space-based power systems, solar-powered aircraft, unmanned aerial vehicles (UAVs), and satellites.