Superhydrophobic Lotus Leaf Structured Foils for Light Management and Self-cleaning in Photovoltaic Devices

Modularly attachable light management and self-cleaning foils are highly desirable for photovoltaic technology. In this work we demonstrate a simple processing method to fabricate a lotus leaf textured fluoropolymer by nanoimprint lithography and hot embossing. We investigated both, light management qualities as well as self-cleaning properties, by comparing foils with lotus leaf structure and random micro-pyramids.Implementation of the lotus leaf textured foil to the sun facing airglass interface of liquid phase crystalized silicon thin-film solar cells was found to increase the short-circuit current density J
sc
from 26.4 mA/cm
²
to 27.3 mA/cm
²
(3.4 % relative gain). At the same time, the contact angle of the planar glass superstrate was improved from 47° to superhydrophobic 157° by the attached lotus foil.