Significantly enhanced performances of semitransparent inverted organic photovoltaic devices have been realized by simply introducing a high reflector structure, which comprises several pairs of MoO3/LiF with a thickness of 60 nm for MoO3 and 90 nm for LiF, respectively. After optimizing the reflector structure, the enhanced light harvesting is achieved, and thus the increased optical current is obtained. The short-circuit current density (JSC) and power conversion efficiency (PCE) are increased to 10.9 mA cm(-2) and 4.32%, compared to 8.09 mA cm(-2) and 3.36% in the control device. This leads to a 30% enhancement in PCE. According to the experimental and simulated results, the improved performance is attributed to the effective reflection of light at the wavelength from 450 to 600 nm, which corresponds to the absorption range of the active layer. The demonstrated light-trapping approach is expected to be an effective method to realize the high efficiency in semitransparent organic photovoltaic devices.