Leaf-structure patterning for antireflective and self-cleaning surfaces on Si-based solar cells

As the naturally evolved sunlight harvester, plant foliage is gifted with dedicated air-leaf interfaces countering light reflections and ambient ruins, yet offering antireflective and self-cleaning prototypes for manmade photovoltaics. In this work, we report on an ecological and bio-inspired coating strategy by replicating leaf structures onto Si-based solar cells. Transparent photopolymer with leaf surface morphologies was tightly cured on Si slabs through a facile double transfer process. After bio-mimicked layer coverages, sunlight reflection drops substantially from more than 35% down to less than 20% once lotus leaf was employed as the master. Consequentially, 10.9% gain of the maximum powers of the photovoltaic is obtained. The leaf replicas inherited their masters' hydrophobicity which is resistant to acidic and basic conditions. Physically adhered dusts are easily removed by water rolling. Lightwave guidance mechanism among air-polymer-Si interfaces is explicated through optical simulations, while wettability through the morphological impacts on hydrophobic states. Taking advantages of varieties of foliage species and surface structures, the work is hoped to boost large-scale industrial designs and realizations of the bionic antireflective and superhydrophobic coating on future solar cells.