Patent US 15/205,233 titled “Tin Perovskite/Silicon Thin-Film Tandem Solar Cell” is part of a “Tandem Series” of high efficiency and cost effective solar cells developed by Solar-Tectic that have the potential to surpass the efficiencies of thin-film solar cell technologies such as CdTe, CIGS, and amorphous silicon to replace mainstream poly and monocrystalline wafers.
The patent is the first for a perovskite layer on crystalline silicon thin-film (tandem) and covers all non-toxic perovskites and inorganic materials.
While there have been many reports of perovskite/silicon (wafer) tandem solar cells (and extensive intellectual property), there has been none on a perovskite/crystalline silicon thin-film tandem solar cell. ST’s thin-film crystalline inorganic bottom layers can be as thin as 20-30 microns with the same or similar efficiency,compared to 300 microns for other wafers, and can be processed at much lower temperatures thereby lowering costs of production significantly. The top perovskite layer is less than 1um and a thin film crystalline silicon (CSiTF) bottom layer decouples the need for a silicon wafer.
An example of the perovskite layer is CsSnBr3 which has a bandgap of 1.75eV, ideally suited as a top layer on silicon thin-film which has a bandgap of 1.12eV. Such a tandem solar cell is capable in theory of 45% efficiency, though ST has set a more realistic 30% efficiency goal, higher than the 26% theoretical limit of silicon wafer technologies.
Importantly, the entire ST process is environmentally friendly since non-toxic Sn (tin) is used to deposit the crystalline silicon thin-film material for the bottom layer in the tandem configuration as well as in the top, perovskite, layer. The more commonly used toxic lead is not used in the perovskite but the processing methods are conventional and similar to those used in today’s thin-film solar cell and display industries.
Recently a patent for a germanium perovskite thin film solar cell was also granted to ST and last year a similar patent was issued for a “Hybrid Organic/Inorganic Eutectic Solar Cell” which is applicable to OLEDs. R&D on the new perovskite thin-film tandem technology has begun at Blue Wave Semiconductors in Maryland.
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