Reducing Interfacial Losses in Solution-Processed Integrated Perovskite-Organic Solar Cells

Low bandgap organic semiconductors have been widely employed to broaden the light response range to utilize much more photons in the inverted perovskite solar cells (PSCs). However, the serious charge recombination at the heterointerface contact between perovskite and organic semiconductors usually leads to large energy loss and limits the device performance. In this work, a titanium chelate, bis(2,4-pentanedionato) titanium(IV) oxide (C₁₀H₁₄O₅Ti), was directly used as an interlayer between the perovskite layer and organic bulk heterojunction layer for the first time. Impressively, it was found that C₁₀H₁₄O₅Ti can not only increase the surface potential of perovskite films but also show a positive passivation effect toward the perovskite film surface. Drawing from the above function, a smoother perovskite active layer with a higher work function was realized upon the use of C₁₀H₁₄O₅Ti. As a result, the C₁₀H₁₄O₅Ti-modified integrated devices show lower interfacial loss and obtain the best power conversion efficiency (PCE) of up to 20.91% with a high voltage of 1.15 V. The research offers a promising strategy to minimize the interfacial loss for the preparation of high-performance perovskite solar cells.