Solution processes for ultrabroadband and omnidirectional graded-index glass lenses with near-zero reflectivity in high concentration photovoltaics

Junwen He, Yuan Yao, Kyu-Tae Lee, Nina Hong, Brent Fisher, Rabab R. Bahabry, Jung Woo Lee, Jeonghyun Kim, Seungyong Han, Sanjay V. Kalidindi, Jae-Hwan Kim, Sung Bong Kim (+7 others)
2018 Scientific Reports  
Concentrator photovoltaic (CPV) systems, where incident direct solar radiation is tightly concentrated onto high-efficiency multi-junction solar cells by geometric optical elements, exhibit the highest efficiencies in converting the sun's energy into electric power. Their energy conversion efficiencies are greatly limited, however, due to Fresnel reflection losses occurring at three air/optics interfaces in the most sophisticated dual-stage CPV platforms. This paper describes a facile one-step
more » ... et-etching process to create a nanoporous surface with a graded-index profile on both flat and curved glasses, with capabilities of achieving ~99% average transmission efficiency in a wide wavelength range from 380 nm to 1.3 µm and for a wide range of incident angles up to ±40° regardless of the polarization state of incident sunlight. The simplicity of the etching process remarkably increases their versatility in various optical elements that require unconventional form factors such as Fresnel lenses and microlens arrays, and/or demanding curvatures along with much reduced dimensions such as ball lenses. Etched glass surfaces on two-stage optical concentrating systems yield enhancements in total optical transmission efficiencies by 13.8% and in the photocurrent by 14.3%, as experimentally determined by measurements on microscale triple-junction solar cells. The presented strategy can be widely adapted in a variety of applications such as image sensors, display systems, and other optoelectronic devices. A recent resurgence of interest in concentrator photovoltaics (CPV) follows from advanced embodiments that increase its potential for use in utility-scale power generation. The most sophisticated systems use geometric optical elements that concentrate solar radiation onto photovoltaic devices with reduced area to allow for the effective use of highly efficient multi-junction (MJ) solar cells. The ability to exploit different semiconductors
doi:10.1038/s41598-018-33200-9 fatcat:7fuwlcafmfbezeckuewdyk3oji