Structural color filters with compensated angle-dependent shifts

TL;DR

This paper presents a method to compensate for angle-dependent spectral shifts in structural color filters by adding a conformal VO2 layer, enabling stable color transmission across different viewing angles.

Contribution

Introducing a VO2 layer onto aluminum structural color filters to counteract spectral shifts caused by changing incident angles, a versatile approach applicable to existing filters.

Findings

VO2 layer compensates spectral shifts at 15° tilt with 80% efficiency

Method is adaptable to existing structural filters without geometric adjustments

Tunable materials can address angle-dependent spectral shifts

Abstract

Structural color filters use nano-sized elements to selectively transmit incident light, offering a scalable, economical and environmentally friendly alternative to traditional pigment- and dye-based color filters. However, their structural nature makes their optical response prone to spectral shifts whenever the angle of incidence varies. We address this issue by introducing a conformal VO2 layer onto bare aluminum structural color filters. The insulator-metal transition of VO2 compensated the spectral shift of the filter's transmission at a 15{\deg} tilt with 80% efficiency. Unlike solutions that require adjustment of the filter's geometry, this method is versatile and suitable also for existing structural filters. Our findings also establish tunable materials in general as a possible solution for angle-dependent spectral shifts.