thin-film photovoltaic

On paper, GaAs (gallium arsenide) thin-film photovoltaic energy has a 33.5% maximum theoretical efficiency, the so-called Shockley-Queisser limit. In other words, it is capable alone, without concentration of light or semiconductor seconds, to transform more than a third of incident energy into electricity. Due to obvious practical limitations, cells manufactured so far have produced significantly lower yields. However, solar researchers are confident that they can reach and bring to market at least 30%. Today, Alta Devices, a subsidiary of the Hanergy group in China, also aspires to this goal.

Thin, flexible and lightweight solar cells, ideal for small stand-alone devices. The importance of efficiency is that the higher it is, the more capable it is of converting sunlight into electricity using the same area.

The company specializes in the production of GaAs thin-film photovoltaic energy and recently set another world efficiency record: certified by the NREL (National Renewable Energy Laboratory), the California-based company produced the first GaAs solar cell with 28.9% conversion efficiency.

Professor Eli Yablonovitch of the University of Berkeley and co-founder of Alta Devices explains the importance of this result:

It is the first solar cell based on the extraction of internal luminescence (“Internal Luminescence Extraction”), which allowed us to maintain an advantage over the others. This scientific principle will be present in all future high efficiency solar cells. Luminescence extraction involves the use of an optical design, such as a rear view mirror or structured surfaces, to help internal photons exit the front surface of a solar cell and thereby increase the efficiency of the conversion. .

Reach a new record for this class of devices – adds Harry Atwater, professor at Caltech and co-founder of the company – it is a benchmark, using standard solar radiation, without concentration. The company uses a chemical vapor deposition process (MOCVD) and epitaxial lift (ELO) technique, which creates a thin, flexible and lightweight solar cell for niche applications as stand-alone devices.. “

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