For the preparation of solar cell absorbers we have three different high-vacuum systems available that allow co-evaporation of the elements or compounds. We have a tube furnace to anneal precursor films. Epitaxial films are grown by metal-organic vapour phase epitaxy (MOCVD).


The solar cell baseline consists of a sputter machine for the metal backcontact and the ZnO conductive window layer at the front, chemical bath deposition of various buffer materials and an electron beam evaporator for metal grids.

Our photoluminescence system is home built with various lasers, including a white laser, as excitation sources and enables intensity and spectral calibration, as well as micrometer spatial resolution. We can measure at ambient temperature or in cryostat down to 10K or in a reaction chamber up to 400K. We use a commercial system for time resolved photoluminescence.


A photospectrometer with integrating sphere and a variable-angle spectral ellipsometer are available to measure the optical properties of the films.

Solar cells are investigated by current-voltage characteristics under an AAA solar simulator, to determine short-circuit current, open-circuit voltage and efficiency. We also measure the spectral quantum efficiency of the current. Current-voltage characteristics are measured at different temperatures to understand activation energies. We measure capacitance of the devices, temperature, voltage and frequency dependent from 100 Hz to a few MHz, to learn about defects and doping. A Hall system with a 9T magnet tells us about doping densities and electron mobilities.