Compatible Solution‐Processed Interface Materials for Improved Efficiency of Polymer Solar Cells

Abstract The electron transport layer (ETL) in an organic solar cell is one of the main components that play a crucial role in the extraction of charges, improving efficiency, and increasing the lifetime of the solar cells. Herein, solution‐processed PBDTTT‐C‐T:PC71BM‐based organic solar cells are fabricated using conjugated PDINO molecules, sol‐gel derived under stoichiometric titanium oxide (TiOx), and a mixture of the same as an ETL. For PBDTTT‐C‐T:PC71BM‐based organic solar cells, a blend of organic‐inorganic ETLs demonstrates reduced bimolecular recombination and trap‐assisted recombination than a single ETL of either two materials. Furthermore, in both, fullerene and nonfullerene systems, the efficiency of the devices employing the blend ETL as compared to the single ETLs show some performance improvement. The strategy of integrating compatible organic and inorganic interface materials to improve device efficiency and lifetime simultaneously, and demonstrate the universality of different systems, has potential significance for the commercial development of organic solar cells.