Flexible ITO films with atomically flat surfaces for high performance flexible perovskite solar cells.

We report high performance flexible Sn-doped In2O3 (ITO) films prepared by in-line type vertical plasma arc ion plating for high performance flexible perovskite solar cells. Even at room temperature deposition, the ion-plated ITO film showed a low sheet resistance of 15.75 Ohm per square, a high average optical transmittance of 85.88% and a small outer bending radius of 5 mm because energetic ITO ions accelerated to the substrate led to better crystallinity and adhesion than sputtered ITO films. In addition, the ion-plated ITO films showed atomically flat and smooth surfaces due to different growth mechanisms and the absence of resputtering effects during the ion plating process. Flexible perovskite solar cells fabricated on the ion-plated ITO electrodes showed a higher power conversion efficiency of 16.8% than the sputtered ITO-based perovskite solar cell, indicating the potential of ion plated ITO films as promising flexible and transparent electrodes for perovskite solar cells.