Broadband Anti-Reflection Coatings Fabricated by Precise Time-Controlled and Oblique-Angle Deposition Methods

Xin Guo,Chi Song,Zizheng Li,Qiang Li,Xiangqian Quan,Binzhi Zhang,Xin Zhang

doi:10.3390/coatings11050492

Abstract

Broadband anti-reflection (AR) coatings are essential elements for improving the photocurrent generation of photovoltaic modules and enhancing visibility in optical devices. In this paper, we report a hybrid-structured, anti-reflection coating that combines multi-layer thin films with a single top-oblique deposited layer. By simply introducing this low-refractive index layer, the broadband anti-reflection properties of optical thin films can be improved while simplifying the preparation. Precise time-controlled and oblique-angle deposition (OAD) methods were used to fabricate the broadband AR coating. By accurately measuring and adjusting the design errors for the thin and thick film layers, 22-layer and 36-layer AR coatings on a sapphire substrate with a 400–2000 nm wideband were obtained. This bottom-up preparation process and AR coating design have the potential to significantly enhance the broadband antireflective properties for many optical systems and reduce the manufacturing cost of broadband AR coatings.

Highlights

Anti-reflection thin film plays a vital role in anti-glare displays [1], automobile dashboards [2], solar cells [3,4,5,6] and most optical systems [7,8,9,10,11]
No simple or feasible method goes into the design of ultra-broadband anti-reflection coatings
There are many ways to control the thickness of optical coatings, including crystal vibration monitoring, and optical monitoring

Summary

Introduction

Anti-reflection thin film plays a vital role in anti-glare displays [1], automobile dashboards [2], solar cells [3,4,5,6] and most optical systems [7,8,9,10,11]. By precisely controlling the refractive index and thickness of each film layer, depositing a coating having four or more layers on a substrate can generally reduce surface reflection to nearly zero over a wide range of wavelengths. No simple or feasible method goes into the design of ultra-broadband anti-reflection coatings. It can only rely on numerical optimization technology to continuously optimize the initial design and even use automatic synthesis technology to generate a film structure that meets the design requirements. The ultra-wideband, anti-reflection characteristics achieved in the final plating process almost entirely depend on the control accuracy of the film thickness [14]. There is an urgent need for an adjustable, low-cost, stable, and repeatable coating process for broadband antireflection coatings

Methods

Results

Conclusion