Energy Level Alignment Regulation and Carrier Management in Perovskite Solar Cells with Various Bandgaps Using Tailored Metal-Organic Frameworks

The interface energy level alignment modulation and charge carrier transportation play an important role in the device performance of perovskite solar cells (PSCs). Herein, tailored hydrophobic metal-organic frameworks (MOFs) are employed as interfacial layers between perovskite absorbers and hole transport layers (HTLs). The tailored MOFs feature abundant carboxylic acid groups capable of bonding with Pb²⁺ and organic cations, which can effectively passivate interface defects and suppress non-radiative recombination. Meanwhile, the MOF interfacial layers optimized the energy level alignment between the perovskite and the HTL, further facilitating carrier transportation. Specifically, the CsFAMA-based PSCs with a bandgap of 1.63 eV attained power conversion efficiency (PCE) of 23.06% upon modification with MOFs. Additionally, the MOFs-treated FA-based PSCs with a bandgap of 1.55 eV achieved a remarkable PCE of 24.81%, accompanied by an outstanding fill factor of 84.3% and a minimal open-circuit voltage loss of merely 0.386 V. Furthermore, the integration of the MOF interfacial layer substantially improved the moisture stability of the PSCs. The unencapsulated CsFAMA PSCs modified with MOFs retained 91.2% of their initial efficiency after 2500 h of aging under ambient conditions with 40% relative humidity (RH). This work underpins the commercialization of PSCs with diverse bandgaps.