Substituents interplay in piperidinyl-perylenediimide as dopant-free hole-selective layer for perovskite solar cells fabrication

The charge selective layer is of significance for the fabrication of emerging photovoltaics, including perovskite-based solar cells. Molecular hole transport materials (HTMs) are being employed as charge transporters, owing to their synthetic molecular flexibility that allows the fine-tuning of their electro-optical properties. Typically, doping of HTMs is essential, but it is a trade-off between long-term durability and device performance. The energetic level of perylenediimides (PDIs) was altered by the position of the substituent. The substituent’s position influences the geometry of the PDI core, which can lose planarity, thus presenting a core twist angle between the two naphthalene subunits to find its application as hole-selective layers for fabrication. We have fabricated perovskite solar cells, with pristine PDI, and it gave a competitive performance. New design protocols for PDIs are required for aligned energetic levels, which will minimize recombination losses in solar cells, favoring a performance enhancement. Graphical abstract