Numerical Study on Broadband Antireflection of Moth-Eye Nanostructured Polymer Film with Flexible Polyethylene Terephthalate Substrate

Jun Lan,Yong Yang,Song Hu

doi:10.3390/nano11123313

Abstract

The application of moth-eye nanostructured polymer film on the flexible polyethylene terephthalate (PET) substrate is an effective way to improve its antireflection (AR) performance. However, many factors affect the AR properties of the moth-eye structure in the actual manufacturing process. Moreover, the antireflection research based on PET substrate has been relatively lacking compared with the silicon substrate. In this paper, we simulate and analyze the AR performance of the moth-eye nanostructured polymer film on PET substrate by using the finite-difference time-domain method within the wavelength range of 400–1100 nm. Simulation results show that the parabola-shaped moth-eye structure (PSMS) can suppress the Fresnel reflection significantly. Moreover, the height and filling ratios are the dominant factors that affect the AR performance of PSMS. Additionally, the base diameter, residual layer thickness, and the refractive index of PSMS polymer film also affect the reflectivity of PET slightly. As a result, an optimal PSMS with base diameter of 400 nm, height of 300 nm, and the hexagonal close-packed arrangement is appropriate, and the solar-weighted reflectivity of PET can be suppressed to 0.21%, which shows a prominent advantage over the bare PET (≈6%). Therefore, this research has promising potential for improving the optical performance of optoelectronic devices by using nanostructured polymer materials.

Highlights

It is well-known that suppression of optical reflection is essential for many optoelectronic devices [1,2,3,4]
It can be seen that when the base diameter is top of polyethylene terephthalate (PET) substrate in the wide wavelength range of 400–1100 nm
Less than 400 nm, the reflectivity is mainly affected by the refractive index of polymer, and array and the design parameters of NOA63 parabolashaped moth-eye structure (PSMS)/PET were optimized by using finite-difference time-domain (FDTD)

Summary

Introduction

It is well-known that suppression of optical reflection is essential for many optoelectronic devices [1,2,3,4]. Multilayer antireflection coatings and biomimetic moth-eye structure (MS) are recognized as two effective methods for reducing reflection in the wide wavelength range. Compared with multilayer antireflection coatings, MS can effectively reduce the Fresnel reflection by forming a gradient refractive index (GRIN) profile between the air and the medium of MS [6]. With the development of technology, optoelectronic devices have gradually transformed to become flexible, ultra-thin, and lightweight. PET is widely employed as device substrate or protection cover in various optoelectronic devices such as solar cells, display panels, transistors, and photodetectors due to its excellent flexibility, light weight, low cost, and high transparency [11,12,13,14].

Methods

Findings

Discussion

Conclusion