Researchers demonstrated record efficiency in flexible solar cells.
Flexible solar cells is a research level technology that has been around for a while. Flexible and lightweight solar modules made of ultra-thin solar cells are especially suited for applications on roofs and facades of buildings, greenhouses, transport vehicles, airships and portable electronics. But one of the major things hampering the progress of this technology is its limited efficiency.
A group of researchers at Empa has pushed the efficiency of flexible solar cells to a new limit. The measurements revealed a power conversion efficiency of 21.4 percent. For comparison: the best efficiency of a non-flexible solar cell made of crystalline silicon is reported at 26.7 percent.
The flexible solar cells are processed on a polymer film by a low temperature co-evaporation method for the growth of a thin film semiconductor that absorbs the light. Researchers optimized the composition of the layer and alkali dopants for achieving performance improvement. They then investigated the effects of combined heat and illumination exposure after the processing of solar cells and found a boost in the photovoltaic performance, which remains stable after several months.
The solar cell efficiency of 21.38 percent was independently measured at Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, Germany.