Vibration treated carbon electrode for highly efficient hole-conductor-free perovskite solar cells

Low temperature printable carbon cathode (CCE) based perovskite solar cells (PSCs) have shown much promise for practical applications, because of their low cost, high stability and the simple fabrication. However, mainly owing to the poor contact of perovskite/carbon interface, the efficiencies of this kind of PSCs are still relatively low, in comparison with the organic hole transport material (HTM)-based PSCs. Here, we employ a novel vibration technique to improve the arrangement of the graphite and carbon black in carbon cathode, leading to increased contact sites of perovskite and carbon layer interface. By optimizing the vibration time acting on the prepared carbon layers, we demonstrate a compact carbon cathode. Perovskite solar cells prepared using the treated carbon layer as counter electrode produce remarkable 22% enhancement in efficiency than those without vibration treatment, improving average power conversion efficiencies from 8.50% to 10.37%.