Tungsten doped indium oxide (IWO) transparent electrode used in air-annealed perovskite solar cells

The common transparent electrode materials used in perovskite solar cells (PSCs), for example, the tin-doped indium oxide (ITO), usually have low carrier mobility and low transmittance in the near-infrared region which limits the short circuit current density (JSC). Accordingly, it is urgent to seek a novel transparent conductive material with high mobility and high transmittance. In this work, the tungsten doped indium oxide (IWO) film, composed of 0.5 wt% WO3 and 99.5 wt% In2O3, is employed in PSCs to act as the transparent electrode. The IWO-based PSCs exhibit superior performance as compared with the ITO-based counterparts mainly due to the excellent opto-electrical properties of IWO, such as high carrier mobility and infrared transmittance, fine surface morphology, etc. The performance of devices is further optimized by air-annealing treatment of the absorber layer. Air-annealing improves the crystallinity, decreases the defect states, and as a result, inhibits the non-radiative recombination. In summary, we fabricated the champion device based on IWO with the JSC of 26.2 mA/cm2 and its power conversion efficiency achieves 23.64%, the maximum record of IWO-based PSCs.