Synergistic Dipole-Defect Engineering via Sulfonic Molecular Bridge Boosts Voltage in Wide-Bandgap Perovskite and All-Perovskite Tandem Solar Cells

Interfacial electric field engineering unlocks high-performance wide-bandgap (WBG) perovskite solar cells (PSCs) for all-perovskite tandem architectures. We introduce 3-sulfopropyl methacrylate potassium salt (SPM), a sulfur-based molecular modulator that creates a dipole-induced built-in electric field at the perovskite/C₆₀ interface while enabling a synergistic regulation of dual-site defect passivation. The vertically aligned sulfonic (-SO₃^-) groups in SPM generate an enhanced interfacial dipole, accelerating charge separation. Moreover, the dual Lewis base sites in SPM interact with uncoordinated Pb²⁺ via lead-oxygen coordination, healing defects, suppressing ion migration, and inhibiting phase segregation. The optimized 1.77 eV-WBG PSCs demonstrate an efficiency of 19.48% with a <i>V</i>_OC of 1.350 V, corresponding to a low <i>V</i>_OC-deficit of 0.420 V. Integrating the dipole-optimized top subcell into all-perovskite tandem solar cells achieves a champion efficiency of 28.90% alongside a high <i>V</i>_OC of 2.158 V.