Asymmetric Conjugated Molecule Co‐Deposition for High‐Performance HTL‐Free Carbon‐Based Perovskite Solar Cells

ABSTRACT Planar hole‐transport‐layer (HTL)‐free carbon‐based perovskite solar cells (C‐PSCs) show great promise due to their chemical stability and cost‐effectiveness. However, the power conversion efficiency (PCE) of HTL‐free C‐PSCs remains limited by severe interfacial nonradiative recombination and inefficient charge extraction. Herein, we designed an asymmetric D−A−D'−A' conjugated molecule 2BCz‐BD and employed a co‐deposition strategy by incorporating 2BCz‐BD into the perovskite precursor solution during film fabrication. The coordination ability of 2BCz‐BD regulates perovskite crystallization and passivates surface defects, thereby suppressing interfacial non‐radiative recombination. The favored p ‐type semiconducting characters also optimize energy‐level alignment to enhance charge extraction. Additionally, the large dipole moment of 2BCz‐BD induces an ordered orientation on the perovskite surface, serving as a template for controlled carbon electrode deposition and enabling high‐quality electrode fabrication. As a result, small‐area (0.062 cm 2 ) and large‐area (1.004 cm 2 ) devices achieved remarkable PCEs of 23.24% and 22.09%, respectively. The unencapsulated devices retained over 90.4% of their initial PCE after 3100 h of operation.