c-PCBSD, a cross-linked fullerene derivative, as a cathodic interlayer in wide-band gap perovskite solar cells

Wide-band gap absorber materials are prerequisites for well-performing tandem photovoltaic devices. Especially, perovskites received huge attention due to their tunable band gap and outstanding optoelectronic properties. Although perovskite solar cells are known to be highly efficient, high-open-circuit voltage losses remain a prevalent issue for wide-band gap perovskites. Within this work, we have investigated the application of the cross-linkable fullerene derivative [6,6]-phenyl-C61-butyric styryl dendron ester (c-PCBSD) as a cathodic interlayer in wide-band gap perovskite solar cells. We could obtain increased open-circuit voltage compared to pristine devices, attributed to fast electron transfer between the perovskite and the interlayer. The changed charge carrier dynamics result in a reduction of non-radiative losses, which consequently decreases the open-circuit voltage loss. Graphical abstract