OPV cells have a proven efficiency of over 18 % while OPV modules have a proven record efficiency of 13.5 %. Both values are still increasing, towards > 20 % for small area cells and > 15 % for large scale modules. Perovskite solar cells have a certified efficiency of over 25 % and first medium sized modules are already beyond 20 %. With these performance values, solution processed photovoltaic is reaching out to applications that are going beyond the typical niche markets. The first generation of commercially available printed PV modules showed a lifespan in the order of beyond 5 years and more under outdoor conditions (OPV). Independent of the application, operational lifetime of organic and perovskite solar cells is not fully understood with respect to the accelerating conditions. Only few publications highlighted operational lifetimes of over 25000 hrs under lab conditions. Interestingly, several experiments are strongly suggesting that solution processed semiconductors like organics or perovskites can be stable under light and, to some extent, under oxygen as well. Unpackaged organic and perovskite solar cells were demonstrated for under-water applications, some of them have been even operated in water and under 1 sun for hundreds of hours. Despite these impressive numbers, one should not forget that these are “best you can do” lifetime values. We have explored the bulk vs interface stability of organic as well as perovskite semiconductors, and found strong evidence that the majority of degradation mechanisms is interface related. This is in quite some discrepancy to the common understanding that organics are not light stable and perovskites not stable against humidity. Nevertheless, we were able to develop rather generic interface materials that demonstrated lifetime records for organics and perovskites. As these two semiconductors are very sensitive to processing, orthogonal solvent processing turned out to be an enabling step. In this work we will report stability investigations on organic and perovskite solar cells for nearly identical hole transport interfaces. Due to the different solubility properties, we had to process the HTL one time from organic and the other time from alcoholic solvents. This talk will give an introduction into nanoparticular organic semiconductors as generic interface materials for printed photovoltaics.