Improving energy level alignment by adenine for efficient and stable perovskite solar cells

NiOx has been widely used as inorganic hole-transport layers (HTLs) in highly efficient hybrid perovskite solar cells (PSCs), however, the solution deposition usually induces pinhole and poor contact with perovskite. In this work, a small organic molecule adenine was used as surface modifier on NiOx substrate for the energy level modulation. After coating adenine, a 0.1 eV energy level drop for NiOx HTL, a higher crystallinity and larger grain size of perovskite layer, and an accelerated charge transport and extraction for device were achieved. Density functional theory (DFT) calculations also confirmed that the crystal structure of perovskite on NiOx/adenine substrate was more stable. These benefits enable a higher open-circuit voltage (Voc) and short-circuit current density (Jsc) in the corresponding devices with significantly enhanced moisture and light stability. Our work provides a novel strategy for modulation of energy level alignment between HTL and perovskites in related photovoltaic and other optoelectronic devices.