Compact gallium arsenide-based photovoltaic converters are capable of generating electricity under the action of laser beams. The minimum size of the converters is 0.2 mm. They will allow the development of technology for wireless power transmission over long distances, which will work even in space.
The method developed by scientists at the Ioffe Institute will not only help provide electricity to satellites and other spacecraft, but also transmit electricity from space to Earth. The results of the study, supported by a grant from the Russian Science Foundation (RSF), have been published in the journal IEEE Electron Device Letters.
It is assumed that one spacecraft in the system will have photovoltaic converters, and the other spacecraft will send a laser to them and charge it. Energy can also be transmitted to Earth.
The converters themselves are a thin trapezoidal layer 45 micrometers thick made of an alloy of aluminum, gallium, and arsenic. They transmit laser radiation through themselves, refracting it in different parts of the waveguide differently depending on the aluminum content in the alloy. This makes it possible to change the trajectory of the laser beam with a wavelength of 0.85 micrometers (infrared part of the spectrum).
The beam is directed to the photoactive part of the converter, which is made of gallium arsenide. When light particles hit gallium arsenide, which has regions with electronic and hole conductivity, they turn into charge carriers, and the energy of light is converted into electric current. Experiments with the size of the photoconverter revealed that the most effective size is 0.2–0.75 mm, its efficiency is about 45%.
Although converters with an efficiency of about 70% are reported abroad, their production process is much more laborious, and the converted power density of the incident laser radiation does not exceed 30 watts per square centimeter. Our technology is simpler, and compared to existing silicon-based analogues, the photovoltaic converters we obtained are 10% more efficient, and the converted power density of the incident radiation reaches 10 kilowatts per square centimeter.
It should be noted that all photoconverters for which an efficiency of about 70% has been achieved have a so-called antireflection coating on the photo-receiving surface, which improves the absorption of incident light, and therefore the efficiency of the converter increases by 20–25 relative percent. We did not apply such a coating in this work for the sake of experimental purity and time saving. Where we did, the efficiency reached 53%.
Scientists plan to obtain more complex assemblies from many individual photocells in order to achieve a higher density of laser radiation and a voltage of tens of volts, which is necessary for more efficient energy transfer to the consumer.
Read materials on the topic:
Russia will entrust AI with the design of digital integrated circuits
Reshetnev tested its new reflectors with membrane reflectors for spacecraft
Increase computing speed: Tomsk has begun developing software for electronics cooling systems