Dimensional Tuning of Perylene Diimide-Based Polymers for Perovskite Solar Cells with Over 24% Efficiency.

The hygroscopic dopants used in Spiro-OMeTAD hole transport material (HTM) in state-of-the-art perovskite solar cells (PSCs) inevitably induce premature degradation of the devices. Here, two multifunctional polymer interface materials based on the perylene diimides (PDI) unit are developed. It is found that quasi-two-dimensional (2D) polymer 2DP-PDI can form a denser film and exhibit better hydrophobicity than linear polymer P-PDI. Importantly, 2DP-PDI can passivate the surface defects and extract hole carriers of perovskite film more effectively, leading to much reduced nonradiative recombination loss. With polymer interface material between the perovskite and HTM layers, the optimized device using 2DP-PDI and P-PDI yields a champion PCE of 24.20% and 23.09%, respectively, along with significantly improved stability, whereas the control device shows a lower efficiency of 22.23%. These results suggest that developing multifunctional polymer interface materials can be a promising strategy to improve the efficiency and stability of PSCs.