Free-Standing Carbon Electrode Modified by Polyvinyl Alcohol for Efficient HTM-Free Perovskite Solar Cells

A free-standing polyvinyl-alcohol (PVA)-modified carbon film with good conductivity has been developed and applied in hole transport material (HTM)-free perovskite solar cells. This free-standing carbon film was hot-pressed onto the methylammonium lead iodide-based perovskite layer as the back contact electrode. Adding PVA during solvent treatment is expected to increase the flexibility and conductivity of the carbon electrodes. An HTM-free perovskite solar cell with a power conversion efficiency (PCE) of 2.83% was obtained, which is higher than a similar cell prepared without PVA modification. This free-standing carbon-modified PVA electrode has the advantages of a low-cost, simple preparation process and shows great feasibility for the up-scaling of perovskite solar cells.