Interfacial Contact Management in Perovskite Solar Cells with Carbon Top Electrode

Perovskite solar cells (PSCs) represent a promising photovoltaic technology that has great potential for mass application. The main advantages of the perovskite solar cells are related to simplicity of their fabrication, tunable optical properties, and low cost of active materials. For further reducing the device costs, graphite‐based contacts are often used to replace an energy‐inefficient deposition of metal contacts, which is a trade‐off between the cost and power conversion efficiency (PCE) of devices. Herein, a new approach to increase the PCE of hole transport layer‐free perovskite cells with carbon‐based electrodes by the sequential treatment of the perovskite absorber layer and perovskite/carbon electrode interface with methylammonium iodide is presented. The proposed passivation technique leads to a dramatic improvement in the device power conversion efficiency from the initial 3.9% to 7.9%. The origin of the enhanced device performance is attributed to the passivation of defects on the perovskite/carbon interface and, most importantly, improving the electrical contact between the top electrode and absorber layer.