High-Performance Perovskite Solar Cells via 3D Covalent Organic Frameworks: Enhanced Efficiency Through Precision Interface Engineering.

Covalent organic frameworks (COFs), a class of porous polymers with tunable 2D or 3D structures, have drawn significant attention for their exceptional versatility across various applications. Recently, the integration of COFs into perovskite solar cells (PSCs) has emerged as a promising strategy to address critical challenges, such as instability, interfacial recombination losses, and lead-associated environmental risks. Enhanced charge transport channels, passivation of defects, and customizable molecule architectures are some of the special benefits that COFs offer. In this study, we used Schiff base reactions to create two donor-acceptor (D-A) type COFs with an 8+2 connection motif, which were integrated into PSC self-assembled (SAM) layers. According to characterizations and theoretical calculations, COFs not only effectively optimize the energy level of the ITO/SAM substrate but also passivate perovskite defects and suppress defect-assisted recombination in PSC devices. These modifications significantly enhanced carrier transport and extraction, resulting in an increase in power conversion efficiency (PCE) from 22.57% to 25.20% (DP-BE) and 24.21% (DP-DBE). This work highlights the potential of COFs as multifunctional modifiers for interfacial engineering in PSCs, offering a promising route to improve device performance and stability.