Solar-Tectic LLC (ST) announced that a patent application for a germanium perovskite thin film tandem solar cell has been allowed by the US Patent and Trademark Office.

Recently perovskite materials have gained much attention as a solution to the longstanding problem of solar cell efficiency, and while there have been reports of perovskite/germanium tandem solar cells, remarkably there have been none on perovskite/crystalline germanium thin-film tandem solar cells. Crystalline thin-film germanium promises to be more efficient and less expensive than silicon and germanium wafer technology due to low temperature processing and less material use. An example of the perovskite layer is CsGeI3.

Importantly, the entire process is non-toxic since germanium is non-toxic and tin (Sn) is used to deposit the crystalline germanium thin-film material for the bottom layer in the tandem configuration; there is no toxic lead (Pb). The technology is the very first of its kind and in addition to the US is also eligible for world-wide protection.