Perovskite-based solar cells absorb light more efficiently than silicon-based solar cells but often cannot convert energy as efficiently due to non-radiative recombination. Defects in the crystal structure can interfere with electrons passing through, converting their energy into heat and reducing the overall output. The solution cooked up by researchers from East China Normal University, Chinese Academy of Sciences and Linköping University (Sweden) to overcome this performance limitation: add capsaicin, the compound responsible for the hot taste of chili peppers, to the cells to improve heat retention.

Researchers added just 0.1% by weight of capsaicin into the precursor of methylammonium lead triiodide Solar cells containing capsaicin. Source: Jin Yang/East China Normal Universityduring the solar cell manufacturing process. The devices were then exposed to artificial light and the electrical current running through them was measured. The recipe proved effective, as the capsaicin rendered the solar cells more efficient, yielding a power conversion of 21.88% versus 19.1% without this ingredient. Spectroscopic analyses revealed the addition of capsaicin increased the number of free electrons available to conduct current at the solar cell surface and reduced energy leakage via heat.

Additional research is needed to fully understand the mechanism by which capsaicin boosted charge transport by reducing the density of defects in the perovskite film and improved the interface between the different semiconductor layers.

The research is published in Joule.