Atomically Dispersed Metal Atoms: Minimizing Interfacial Charge Transport Barrier for Efficient Carbon-Based Perovskite Solar Cells.

Carbon-based perovskite solar cells (C-PSCs) exhibit notable stability and durability. However, the power conversion efficiency (PCE) is significantly hindered by energy level mismatches, which result in interfacial charge transport barriers at the electrode-related interfaces. Herein, we report a back electrode that utilizes atomically dispersed metallic cobalt (Co) in carbon nanosheets (Co/CN) to adjust the interfacial energy levels. The electrons in the d-orbitals of Co atoms disrupt the electronic symmetry of the carbon nanosheets (CN), inducing a redistribution of the electronic density of states that leads to a downward shift in the Fermi level and a significantly reduced interfacial energy barrier. As a result, the C-PSCs using Co/CN as back electrodes achieve a notable PCE of 22.61% with exceptional long-term stability, maintaining 94.4% of their initial efficiency after 1000 h of continuous illumination without encapsulation. This work provides a promising universal method to regulate the energy level of carbon electrodes for C-PSCs and paves the way for more efficient, stable, and scalable solar technologies toward commercialization.