A team of researchers from UNIST in South Korea has identified a tin-based perovskite which could open new possibilities for the application of lead-free perovskites in solar cells. The cesium-tin based double perovskite material, Cs2SnI6, had previously been identified as promising for use in solar cells, however little research into the perovskite’s surface properties had been carried out.

UNIST team demonstrates new lead-free perovskite image

The team created a three-electrode system allowing them to confirm that charge transfer occurred through the surface state of the material; and used this knowledge to engineer a Cs2SnI6 based organic dye sensitized solar cell.

“Due to a high volume of electrical charges in organic dyes that show high connectivity with the surface state of Cs2SnI6, more electric current were generated,” says Byung-Man Kim in the Department of Chemistry at UNIST, a lead author of this study. “Consequently, Cs2SnI6 shows efficient charge transfer with a thermodynamically favorable charge acceptor level, achieving a 79% enhancement in the photocurrent density compared with that of a conventional liquid electrolyte.”

This study was said to be one of the first into the charge transfer mechanism of Cs2SnI6, and its results suggest that the surface state is a key issue to be considered in the design of such devices.