Breaking shockley-quisser barrier with cryogenic silicon solar cells
Researchers from Taizhou University and the University of Delaware have reported the first experimental solar cell to exceed the long-term Shockley-quisser-efficiency ceiling for devices with one junction. Their N-type monocrystalline silicon cells achieved 50-60 percent power conversion efficiency in cryogenic temperatures of 30-50 K, almost doubled the best record of the room temperature.
The study destroys conventional thinking that photovoltaic performance collapses at low temperatures. Conventional cells suffer from around 150 K by the carrier direction, but the new design changes this regime into an advantage. Suppresses fonon populations, slows the cooling of the hot-carrier, so that the open circuit voltage can approach the silicon band-gap energy.
The most important innovations are cryogen hot-carier management, with lasers that are just above the band GAP tailored to generating mobile photo barriers that prevent rapid cooling. At temperatures below 50 K, relaxing momentum retention may make impactiveization possible, so that photons near 980 Nm can activate multiple excitons, which increases external quantum efficiency more than 140 percent.
The micro-thin cells, less than 3 microns thick, were optimized with 635 Nm lighting to balance the penetration depth and absorption, so that freezing out effects are minimized. It is important that their performance remained stable about light intensities from 0.01 to 1 sun, which suggests that applications from lunar survey to deep space probes suggest where star light is the only power source.
Potential applications vary from feeding robbers in permanently shadow moon craters with reflected light, to reliable energy for super -conducting electronics and quantum instruments at extreme low temperatures. The research team now scales up to 4 cm2 cells for environmental tests under thermal bicycles and proton radiation, with NASA Commercial Lunar Payload Services as a target application.
Research report:The efficiency limit of Shockley-Questa cells surpassed
