Benefiting from the advantages of low cost, light weight and mechanical flexibility, piezoelectric nanogenerators have the potential for application in renewable energy harvesting from various unexplored sources. Here, we report the demonstration of the record efficiency of flexible piezoelectric nanogenerators (PENG) using composites of polyvinylidene fluoride (PVDF) and chemically exfoliated tungsten disulfide (WS2) nanosheets, which are found to be strongly photosensitive, making them attractive for self-powered optical devices. The presence of two-dimensional (2D) WS2 nanosheets in the PVDF matrix plays a dual role in enhancing the nucleation of the electroactive β-phase as well as inducing strong photosensitivity in the nanocomposite. The PVDF-WS2 composed flexible device is able to produce an enormously high output voltage of ∼116 V (for an impact of 105 kPa) and a piezoelectric energy …