Despite significant advancements in inverted perovskite solar cells, their commercialization remains hindered by low efficiency and stability issues stemming from inadequate crystallization and unfavorable interfacial states. Researchers Huang Shaoming from the Chinese Academy of Sciences, Kang Zhuo from the University of Science and Technology Beijing, and Wu Hualin from Guangdong University of Technology have synthesized a hydrazone-linked covalent organic framework (COF) named 12-SD-COF, featuring long-chain alkyl phosphate branches. This material was integrated into perovskite precursors to achieve synergistic multidimensional regulation of crystallization, defect states, and charge separation.
The study highlights the following key findings:
Researchers discovered that 12-SD-COF, characterized by periodic pores, large planar structures, and abundant binding groups, extrudes from the precursor solution to deposit at buried interfaces, surfaces, and grain boundaries. This process facilitates oriented crystallization while eliminating perovskite defects, resulting in high-quality crystals that suppress nonradiative recombination. Simultaneously, the optimized energy level alignment from p-type doping and the induced intramolecular electric field synergistically enhance interfacial charge separation, culminating in a power conversion efficiency (PCE) of 26.21%.
Furthermore, the obtained unencapsulated devices demonstrated excellent stability, retaining over 92% of their initial PCE after aging under continuous heating stress at 85°C for 800 hours, exposure to 50±3% relative humidity for 1000 hours, and continuous 1-sun illumination for 1200 hours.
