Effect of an Ultra-thin Molybdenum Trioxide Layer and Illumination Intensity on the Performance of Organic Photovoltaic Devices

The effect of an ultra-thin molybdenum trioxide (MoO3) layer thickness inserted between the indium tin oxide (ITO) substrate and copper phthalocyanine (CuPc) layer on the performance of organic photovoltaic devices (OPVs) was studied. Experimental results demonstrate that the short-circuit current density (J sc) was decreased slightly with the increase of MoO3 thickness; meanwhile, the fill factor (FF) was increased from 53.5 to 57.7%, respectively, leading to the improved power conversion efficiency with the optimal thickness of MoO3 (1 nm). The experimental results also reveal that the Ohmic contact is formed with the deposition of MoO3. Further, the effect of the MoO3 layer was checked from the variation of the performance of OPVs under different illumination intensities. It was found that the MoO3 layer could effectively prevent exciton quenching at the ITO anode side, resulting in the small variation of the FF for the devices with the MoO3 layer compared to the devices without the MoO3 layer under high illumination intensity.