The realization of efficient single and tandem cells based on perovskites relies significantly on matching the electronic energy levels in the
entire device stack. Proper electrical contact between the electrodes must be established, which will require the development of methods to optimize interface energy levels. For
tandem cells the center-connecting electrode should possess proper charge generation / charge recombination functionality, which will also require energy level tuning.
In this project, the energy levels at all interfaces within single and tandem solar cells will be determined, mainly using ultraviolet photoelectron
spectroscopy (UPS), with complementary methods such as Kelvin-probe and photoelectron yield spectroscopy. Once the mechanisms that govern the level alignment are understood, means
to tune the interface electronic states will be evaluated, mainly based on the introduction of strong molecular donors and acceptors.