Hybrid energy harvester with bi-functional nano-wrinkled anti-reflective PDMS film for enhancing energies conversion from sunlight and raindrops

The hybrid energy harvester composed of a solar cell and a water-drop triboelectric nanogenerator (WD-TENG) has been reported to harvest energy from sunlight or raindrops depends on the changing natural environment. However, the reported integrated WD-TENGs always reduce the light absorption of solar cells, resulting in a decline of solar cell efficiency. Here, a bi-functional nano-wrinkled polydimethylsiloxane (nw-PDMS) film is introduced to fabricate the hybrid energy harvester, serving as both the anti-reflective layer of the solar cell and the triboelectric layer of the WD-TENG, and simultaneously enhancing the energy harvesting efficiency from sunlight and raindrop. With significantly enhanced transmittance due to the anti-reflective coating, the power conversion efficiency of the solar cell has improved from 12.55% to 13.57%. In addition, due to the high aspect ratio, surface fluorination and strong hydrophobicity of the nw-PDMS film, both open circuit voltage (VOC-T ) and short-circuit current (ISC-T) of the WD-TENG have huge enhancement by 385.5% and 299.1%, respectively. In this work, the introducing of bi-functional nw-PDMS film provides a simple and convenient strategy for designing hybrid energy harvester with enhanced output performances, which is a general route for Si-based solar cell and other kinds of solar cells.