Thin film solar cells

Empa's focus is on highly efficient thin film solar cells that can be manufactured on both rigid substrates and light-weight flexible polymer or metal foils, making them attractive for terrestrial, portable as well as space applications.
CIGS solar cells
Solar cells based on CuIn1-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).
Perovskite solar cells
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 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.
CZTS solar cells
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%.
Tandem solar cells

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.

Prof. Dr. Ayodhya N. Tiwari

Prof. Dr. Ayodhya N. Tiwari
Head of Laboratory

Phone: +41 58 765 4130