Anti‐Dissociation Passivation via Bidentate Anchoring for Efficient Carbon‐Based CsPbI_2.6Br_0.4 Solar Cells

Abstract Molecular passivation on perovskite surface is an effective strategy to inhibit surface defect‐assisted recombination and reduce nonradiative recombination loss in perovskite solar cells (PSCs). However, the majority of passivating molecules bind to perovskite surface through weak interactions, resulting in weak passivation effects and susceptible to interference from various factors. Especially in carbon‐based perovskite solar cells (C‐PSCs), the molecular passivation effect is more susceptible to disturbance in subsequent harsh preparation of carbon electrodes via blade‐coating route. Herein, bidentate ligand 2,2′‐Bipyridine (2Bipy) is explored to passivate surface defects of CsPbI_2.6Br_0.4 perovskite films. The results indicate that compared with monodentate pyridine (Py), bidentate 2Bipy shows a stronger chelation with uncoordinated Pb(II) defects and exhibits a greater passivation effect on perovskite surface. As a result, 2Bipy‐modified perovskite films display a significantly boosted photoluminescence lifetime, accompanied by excellent anchoring stability and anti‐dissociation of passivating molecules. Meanwhile, the moisture resistance of the 2Bipy‐modified perovskite films is also significantly enhanced. Consequently, the efficiency of C‐PSCs is improved to 16.57% (J_sc = 17.16 mA cm⁻², V_oc = 1.198 V, FF = 80.63%). As far as it is known, this value represents a new record efficiency for hole transport material‐free inorganic C‐PSCs.