Electronegativity‐Guided Molecular Passivation and Bridging for the Enhanced Performance of Carbon‐Based Hole‐Transport‐Layer‐Free CsPbI 2 Br Solar Cells

Br grain dimensions alongside enhanced surface density and reduced roughness. BDPA exhibits superior passivation efficacy due to the reduced electronegativity of its central phosphorus atom, strengthening oxygen coordination capability. Consequently, the BDPA-optimized device delivers a leading PCE of 15.55%, ≈24% increment over 11.80% for the control device, as well as the improved operational stability and reduced current-voltage hysteresis.