Influence of TiOx and Ti cathode interlayers on the performance and stability of hybrid solar cells

The performance of organic and hybrid solar cells is, in addition to the properties of the absorber layer, also strongly dependent on electrodes and interlayers extracting the charges generated in the absorber layer. Here, we investigate Ti and TiOx interlayers regarding the performance and stability of polymer/copper indium sulfide hybrid solar cells with aluminum and silver electrodes. For this, TiOx interlayers were prepared via thermal evaporation of titanium under moderate vacuum conditions in oxygen containing atmosphere, whereas Ti interlayers were deposited under high vacuum conditions. The titanium-based interlayers improved the power conversion efficiencies of solar cells with Al as well as with Ag electrodes. Also the stability of solar cells with Al electrodes was improved; however, solar cells with Ag electrodes and TiOx as well as Ti interlayers turned out to be much more stable and showed lifetimes of several thousand hours under continuous illumination.