Various flexible energy-harvesting technologies can convert ambient energy into electricity. These include solar cells for harvesting light energy, triboelectrics and piezoelectrics for harvesting mechanical energy, thermoelectrics and pyroelectrics for capturing thermal energy and biofuel cells for converting biochemical energy. Light, heat, vibration, body movement or even sweat can be sources of energy in daily life. We are aiming at developing highly efficient flexible soalr cells, triboelectric nanogenerators and hydrovoltaics toutilize such abundant, intermittent and randomly distributed energy sources.