A team of scientists led by researchers from the Complutense University of Madrid (Universidad Complutense de Madrid) has created the world’s first solar cell using gallium phosphide and titanium. This compound is capable of almost doubling the efficiency of silicon, promising a maximum efficiency of close to 60% for a single pn junction.
Image source: Universidad Complutense de Madrid
«Our group has been researching these elements for more than 15 years,” Javier Olea Ariza, lead author of the study, told PV Magazine. “We published the first article in the series in 2009, and in our last article we moved on to creating the first real devices. The devices are still performing poorly and their current efficiency is very low. Although more work is required, the theoretical potential of these elements could reach an efficiency of about 60%.”
The most popular material for the production of solar cells is silicon. The band gap of silicon is 1.1 eV (electron volts). According to the Shockley-Quisser limit, this gives the maximum theoretical efficiency limit for a single silicon pn junction of about 32%. Above this value, there is no simple way to obtain greater efficiency for a solar panel. It is necessary to superimpose several transitions on top of each other to absorb different ranges of light or, for example, to focus the light – increase its intensity in one way or another.
If scientists can develop single junctions based on GaP:Ti, then with its band gap of 2.26 eV, the conversion efficiency of a single junction promises to rise to 60%. But so far only a small part of the work has been done to move towards this incredible result. Scientists have only recorded that an early prototype GaP:Ti cell with an area of u200bu200b1 cm2 is capable of efficiently absorbing photons for photoelectric conversion both below 550 nm and in a narrow band above this mark. Apparently, titanium is responsible for the latter. Researchers will begin to work on creating a prototype of a new element with higher efficiency, with which it will be possible to think about something more than silicon.