Single crystal monolithic upconverter solar cell device tandems with integrated optics

Solar photons possessing energy less than the bandgap of a single-junction solar cell can be utilized via upconversion (UC) two or more photons, resulting in emission single above-bandgap photon. Due to non-linear nature UC, highly concentrated light is required, which typically much greater practical concentration limits cell. It has been proposed that concentrating cells (UC-SC) with optical elements integrated into device could help realize high irradiance required. To avoid scattering problems arising from common UC materials based on micro-crystalline powders, this work, concentrators are investigated mono-crystalline upconverters silicon-based tandem devices. An external quantum efficiency (EQE) 6% 1493 nm infrared illumination at 876 W / mathvariant="normal">m 2 was obtained upconverter concave optics. At an higher 90 (equivalent 2.95 × 1450–1600 range), non-concentrating UC-SC exhibited 1 . 5 EQE compound parabolic concentrator (CPC), while below CPC 1.95 reference device. negligible layer, distribution localized revealed along its effect performance found accumulated within first mm layer peaks variable depths according scheme. These results suggest ample space for improved devices by using