Effect of MoO₃ doping power on the electrical, optical, and structural properties of MoO₃-doped In₂O₃ anodes for organic solar cells

The authors investigated the effects of MoO₃ doping power on the electrical, optical, and structural properties of MoO₃-doped In ₂O₃ (IMO) films for use as transparent electrodes in organic solar cells (OSCs). By optimizing the RF power of the MoO₃ target (30 W), they obtained IMO films with sheet resistance of 24.57 Ω/sq and optical transmittance of 81.57, comparable to conventional Sn-doped In ₂O₃ (ITO) electrodes. In particular, the IMO film exhibited a high optical transmittance in the near-infrared (NIR) wavelength region due to the effects of Mo dopant with high Lewis acid strength and high mobility. In addition, strongly oriented (222) grains led to a smooth surface of the IMO electrode with root mean square roughness of 2.344 nm. The OSC fabricated on the optimized IMO electrode showed cell performances with a fill factor of 64.66, a short circuit current of 8.058 mA/cm², an open circuit voltage of 0.611 V, and a power conversion efficiency of 3.186, which are nearly identical to OSCs with an ITO reference. This indicates that the IMO film is a promising alternative to the ITO electrode for the tandem OSC absorbing NIR wavelength region.