Clarifying perovskite films

• Photovoltaics emphatically adds to lasting power supply. The performance of solar cells in straight converting light energy right into electric power depends upon the product made use of. Metal-halide perovskites are considered really encouraging materials for solar cells of the future generation. With these semiconductors called after their unique crystal structure, a significant boost in efficiency was attained in the past years.

Meanwhile, perovskite solar cells have reached an efficiency of as much as 25.5 percent, which is fairly near to that of silicon solar cells that are presently controling the market. Furthermore, the products needed for perovskite solar cells are instead bountiful.

The solar cells can be produced conveniently and also at low cost and also they can be used for numerous applications. The in theory achievable efficiency of perovskite solar cells is about 30.5 percent.

To approach this worth, optoelectronic quality of perovskite semiconductors should be additionally boosted. In principle, materials fit for photovoltaics are expected to not just soak up light, but to likewise produce it successfully. This procedure is known as photoluminescence. The equivalent specification, photoluminescence quantum performance, is perfectly fit to identify the quality of perovskite semiconductors.

Together with researchers from the Center for Advanced Materials (CAM) of Heidelberg University and the Technical University of Dresden, researchers of KIT's Institute of Microstructure Technology (IMT) as well as Light Technology Institute (LTI) have actually now created a version, by means of which photoluminescence quantum performance of perovskite films can be established reliably as well as exactly for the very first time. Their results are reported in Matter.

Materials Have Even More Optimization Possibilities than Assumed

" With the help of our model, photoluminescence quantum effectiveness under solar irradiation can be figured out even more precisely," states Dr. Paul Fassl from IMT. "Photon recycling is of high relevance. This is the share of photons discharged by the perovskite, which is re-absorbed and re-emitted in the thin films."

The researchers applied their version to methylammonium lead triiodide (CH3NH3PbI3), among the perovskites of highest possible photoluminescence quantum performance. Up until now, it has actually been approximated to amount to regarding 90 percent.

Version estimations, nonetheless, exposed that it has to do with 78 percent. The scientists explain that previous estimations did not properly think about the effect of light spreading and, hence, underestimated the possibility of photons - the quantums of light power - leaving the film prior to they are re-absorbed.

"Our results reveal that the possibility for optimization of these products is much greater than presumed," states Dr. Ulrich W. Paetzold, Head of the Advanced Optics and Materials for Future Generation Photovoltaics Group of IMT. The group offers an open-source application based upon the model, through which photoluminescence quantum performances of numerous perovskite products can be determined.