Self-cleaning hybrid energy harvester to generate power from raindrop and sunlight

Energy harvesting techniques have attracted great deal of attention for sustainable energy security. Among those techniques, solar cell is most widely used energy harvesting device. However, power conversion efficiency of solar cell is seriously affected by weather conditions and contamination from airborne dust. In this paper, hybrid cell, which has high immunity against weather condition and contamination by simultaneously harvesting raindrop and solar energy, is proposed. The hybrid cell consists of transparent triboelectric nanogenerator (TENG) and conventional solar cell. The transparent TENG is fabricated with superhydrophobic PDMS and ITO/PEN substrate. Output voltage are current were 7 V and 128 nA, respectively. Maximum output power is 0.27 μW. Also, output characteristics of water TENG is investigated with various solutions including actual rainwater and flowing water to explore realistic potential of water TENG in harvesting actual raindrop energy. Moreover, enhanced cleaning effect of hybrid cell is experimentally demonstrated with the carbon powder for the first time and hybrid cell successfully harvested both energy without any cross-effect. These results suggest great potential of water TENG in actual environment and insight into utilizing superhydrophobic surface of water TENG.