Enhanced Interfacial Charge Transfer Dynamics of Carbon‐Based Hole Transport Layer‐Free All‐Inorganic Perovskite Solar Cells Prepared in Air

ABSTRACT Carbon‐based all‐inorganic CsPbI 2.2 Br 0.8 perovskite solar cells (PSCs) are promising for low‐cost photovoltaics but suffer from interfacial defects, inefficient charge transfer, and poor environmental stability. This work adopted three types of conjugated molecules with different conjugation degrees and steric configuration: Stilbene (Stb), Triphenylethylene (TPE), and Tetraphenylethylene (TPEE) as interfacial modifiers for fabricating CsPbI 2.2 Br 0.8 films via the hot air‐assisted spin‐coating method. TPEE modification yielded the most homogeneous perovskite films with enhanced crystallinity and prolonged carrier lifetime by suppressing non‐radiative recombination. TPEE also optimized energy alignment between CsPbI 2.2 Br 0.8 and the carbon electrode, decreasing the charge transfer barrier. Owing to the benefits of modification, the TPEE‐modified carbon‐electrode PSCs achieved a maximum power conversion efficiency (PCE) of 14.67%, outperforming the pristine devices’ PCE value of 11.87%. Furthermore, the TPEE‐modified device exhibited long‐term stability. It retained 80.73% of its initial power conversion efficiency (PCE) after 600 h in ambient air (30% relative humidity (RH)) (vs 31.89% for the pristine device), and 83.24% of its initial PCE after 1,000 h in glove box (ves 50.04% for the pristine device), due to the high hydrophobicity of the TPEE. TPEE's four phenyl groups enable optimal defect passivation, energy level alignment, and moisture resistance, offering a scalable strategy for high‐performance stable carbon‐electrode all‐inorganic PSCs. This work provides a facile and effective strategy for interface engineering of all‐inorganic PSCs using conjugated molecules, highlighting the critical role of molecular structure and energy level matching in improving charge transfer dynamics and environmental stability, establishing a molecular structure‐device performance relationship, and paving a new way for the development of high‐efficiency and stable carbon‐electroded PSCs.