Dissolvable molecular bridges promoting buried interface modification for high-performance inverted perovskite solar cells

Abstract

Non-radiative recombination and suboptimal interfacial contact at the hole transportation layer (HTL)/perovskite interface critically suppress the device performance and stability of inverted perovskite solar cells (PSCs). Herein, we proposed a dissolvable molecular bridge (DMB) strategy by introducing 4-fluorobenzylphosphonic acid (4F-BPA) on the HTL for synergetic buried interface modification, aiming at both defect passivation and interfacial contact enhancement. Comprehensive characterizations and analyses revealed that approximately 80% of 4F-BPA on the HTL was dissolved into the perovskite precursor, promoting controlled crystallization through intermediate phase formation and predominantly accumulating at the HTL/perovskite interface, where it strongly coordinated with lead(II) cations to enhance the interfacial contact and align the energy levels. As a result, the champion device achieved a power conversion efficiency (PCE) of 25.10% with a fill factor of 84.23%. The unencapsulated devices (also without a UV filter) maintained 87.1% of their initial PCE after 1000 h of maximum power point tracking under 1 sun illumination (ISOS-L-1I) and retained 92.7% of their initial PCE after 1000 h in the dark storage test (ISOS-D-1). The DMB strategy establishes a universal and cost-efficient framework for buried interface engineering, unlocking new possibilities for large-area device fabrication and industrial-scale implementation.