Large block copolymer self-assembly for fabrication of subwavelength nanostructures for applications in optics
Collins, Timothy W.
Morris, Michael A.
American Chemical Society (ACS)
Nanostructured surfaces are common in nature and exhibit properties such as antireflectivity (moth eyes), self-cleaning (lotus leaf), iridescent colors (butterfly wings), and water harvesting (desert beetles). We now understand such properties and can mimic some of these natural structures in the laboratory. However, these synthetic structures are limited since they are not easily mass produced over large areas due to the limited scalability of current technologies such as UV-lithography, the high cost of infrastructure, and the difficulty in nonplanar surfaces. Here, we report a solution process based on block copolymer (BCP) self-assembly to fabricate subwavelength structures on large areas of optical and curved surfaces with feature sizes and spacings designed to efficiently scatter visible light. Si nanopillars (SiNPs) with diameters of ∼115 ± 19 nm, periodicity of 180 ± 18 nm, and aspect ratio of 2–15 show a reduction in reflectivity by a factor of 100, <0.16% between 400 and 900 nm at an angle of incidence of 30°. Significantly, the reflectivity remains below 1.75% up to incident angles of 75°. Modeling the efficiency of a SiNP PV suggests a 24.6% increase in efficiency, representing a 3.52% (absolute) or 16.7% (relative) increase in electrical energy output from the PV system compared to AR-coated device.
Subwavelength nanostructures , Antireflective surfaces , Reflectivity , Omnidirectional , Graded refractive index , Block copolymers , Optics
Mokarian-Tabari, P., Senthamaraikannan, R., Glynn, C., Collins, T. W., Cummins, C., Nugent, D., O’Dwyer, C. and Morris, M. A. (2017) 'Large Block Copolymer Self-Assembly for Fabrication of Subwavelength Nanostructures for Applications in Optics', Nano Letters, 17(5), pp. 2973-2978. doi: 10.1021/acs.nanolett.7b00226
© 2017 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Nano Letters, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/pdf/10.1021/acs.nanolett.7b00226