Solar cells based on CuIn_1-xGaxSe₂ (CIGS) absorbers exhibit the highest efficiencies and performance stabilities among all thin-film technologies. Empa has developed a deposition process for CIGS solar cells, which is suitable for high-speed roll-to-roll production on low-cost polymer and metal foils. World record efficiency of 20.4% was achieved for a flexible CIGS cell thanks for an innovative post-depositon treatment (PDT). This PDT process contributed to worldwide efficiency improvements by different labs, enabling the current record 22.8% on glass substrates (Solar Frontier, 2016).

Organometallic halide perovskites is an emerging thin film technology that has demonstrated an unprecedented rise in conversion efficiency to > 22% just in several years thanks to unique opto-electronic properties of the perovskite materials. Our research focus is on novel deposition processes as well as semi-transparent perovskite devices suitable for the next generation of super-high efficiency thin film solar cells.

CdTe is a proven photovoltaic technology with annual global production of 3 GWp in 2015, which has the lowest energy payback time of all mass-produced PV technologies. Our focus is on innovative device structures and fast deposition processes for CdTe solar cells in so-called superstrate and substrate configurations on both rigid and flexible substrates.

Solar cells based on Cu₂ZnSn(S,Se)₄ absorbers – also called kesterites –  are composed of earth-abundant elements, and therefore considered as a low-cost alternative to the CIGS technology albeit their efficiency should certainly be improved beyond the currently demonstrated efficiencies of 11-12%.

Super high efficiency > 30% can be achieved with tandem or multijunction solar cells. Perovskite and CIGS cells have complementary spectral response and therefore are suitable for building tandem devices in 2- and 4-terminal configuration.

Thin film solar cells are especially attractive for all applications where high-efficiency, module flexibility, lightweight and affordable cost are desirable, ranging from portable electronics for outdoor and indoor use, automotive, PV-integrated products to space applications. Flexible CIGS technology of Empa is exploited by company Flisom AG targeting the rapidly-growing market of building integrated photovoltaics (BIPV). More informations on thin film solar cell can be found in the Laboratory for Thin Films and Photovoltaics.