title: Multiscale ommatidial arrays with broadband and omnidirectional antireflection and antifogging properties by sacrificial layer mediated nanoimprinting.
abstract: Moth's eye inspired multiscale ommatidial arrays offer multifunctional properties of great significance in optoelectronic devices. However, a major challenge remains in fabricating these arrays on large-area substrates using a simple and scalable technique. Here we present the fabrication of these multiscale ommatidial arrays over large areas by a distinct approach called sacrificial layer mediated nanoimprinting, which involves nanoimprinting aided by a sacrificial layer. The fabricated arrays exhibited excellent pattern uniformity over the entire patterned area. Optimum dimensions of the multiscale ommatidial arrays determined by the finite-difference time domain simulations served as the design parameters for replicating the arrays on glass. A broadband suppression of reflectance to a minimum of ∼1.4% and omnidirectional antireflection for highly oblique angles of incidence up to 70° were achieved. In addition, superhydrophobicity and superior antifogging characteristics enabled the retention of optical properties even in wet and humid conditions, suggesting reliable optical performance in practical outdoor conditions. We anticipate that these properties could potentially enhance the performance of optoelectronic devices and minimize the influence of in-service conditions. Additionally, as our technique is solely nanoimprinting-based, it may enable scalable and high-throughput fabrication of multiscale ommatidial arrays.
authors: Department of Mechanical Engineering, National University of Singapore , Singapore 117574, Republic of Singapore.
authors: Hemant Kumar
authors: HK
authors: Raut
authors: Saman Safari
authors: SS
authors: Dinachali
authors: Yee Chong
authors: YC
authors: Loke
authors: Ramakrishnan
authors: R
authors: Ganesan
authors: Kwadwo Konadu
authors: KK
authors: Ansah-Antwi
authors: Aleksander
authors: A
authors: Góra
authors: Eng Huat
authors: EH
authors: Khoo
authors: V Anand
authors: VA
authors: Ganesh
authors: Mohammad S M
authors: MS
authors: Saifullah
authors: Seeram
authors: S
authors: Ramakrishna
mesh_terms: D000818:Animals; D032701:Biomimetics / Q000379:methods*; D005123:Eye; D006813:Humidity; D057927:Hydrophobic and Hydrophilic Interactions; D009036:Moths; D036103:Nanotechnology / Q000379:methods*; D055620:Optical Phenomena; D011076:Polycarboxylate Cement / Q000737:chemistry
chemical_list: D011076:Polycarboxylate Cement; C005506:polycarbonate
keywords: biomimetics; hierarchical patterning; moth’s eye antireflection; nanoimprint lithography; superhydrophobicity