In solar photovoltaic systems, enhancing absorption of the incident light on the device surface through reducing reflection is crucial for improving the system performance. In the traditional layered method for anti-reflective coatings (ARCs), however, there are not a few limitations in achieving ARCs, because it depends on the wavelength, angle, and polarization of the incident light. On the contrary, the bio-inspired nanostructures provide amazing multifunctional properties as well as those overcoming the limitations of the traditional layered ARCs, e.g. broadband and quasi-omnidirectional antireflection, hydrophilicity-based antifogging, and super-hydrophobicity-based self-cleaning in combination with optical, mechanical, and adhesion properties. When it comes to anti-reflective properties, especially moth-eye nanostructures exhibit exceptional broadband and wide-angle performances compared to the conventional ARCs. In the present work, using polydimethylsiloxane (PDMS) with such advantageous material properties to this concept as easily controllable morphology, adherence to the flexible substrate, ease of large-area fabrication and so on, moth-eye nano-patterned ARCs which are protuberant, aspect ratio >1 long and truncated corn-like shape are fabricated for both the photovoltaic performance enhancement and the device surface protection. Here, the nanostructured PDMS sticker was replicated by soft imprint lithography using Si master prepared through self-assembly lithography with three different sizes of polysterene (PS) beads. There are two novelties in this work. The first, in contrast with the previously reported ARCs which are fixed in the device itself, the moth-eye nano-patterned PDMS ARC of this work is free from the device just like a sticker with the ability both repeatedly attachable and easily detachable even to any kind of device shape. And the second, it is state of the art to make the protuberantly nano-patterned PDMS with high aspect ratio (>1), taking into account the fabrication difficulty attributed to PDMS nanostructures’ collapse and clustering while hollow patterns on PDMS are well researched. The PDMS film of this work is expected widely applicable thus useful to such devices as flat panel displays, photodetectors, photovoltaics, etc.
Journal: TechConnect Briefs
Volume: 4, Informatics, Electronics and Microsystems: TechConnect Briefs 2018
Published: May 13, 2018
Pages: 197 - 200
Industry sector: Sensors, MEMS, Electronics
Topics: Photonic Materials & Devices