Hole transport layers based on metal Schiff base complexes in perovskite solar cells

In this report a new series of metal Schiff base complexes (MMePy, M = Pt, Pd and Cu) were synthesized and used as hole transport materials (HTMs) in perovskite solar cells (PSCs), as an attempt to realize the hole extraction and transport ability of these materials in PSCs. The energy levels of the materials can be easily tuned by changing the central metal, leading to a better alignment with the perovskite absorber. The well matching of energy level along with lower surface roughness and higher crystallinity of the thin film give rise to the highest PCE of 8.07 % for the CuMePy-based device among the MMePy-based devices. The result indicates the promising application of this series of metal complexes for the use as HTM in PSCs.