High-Efficiency Bragg Mirrors by Solution-Based and Roll-to-Roll Processing

Developing solution-processed Bragg mirrors with high refractive index contrasts (ΔRI) and thermal stability while ensuring time-efficient processing and scalability is challenging. We address these limitations by engineering high RI titanium dioxide nanoparticle-based layers and low RI mesoporous silicon dioxide layers, successfully stacking up to 11 layers utilizing spin coating, as well as roll-to-roll high-throughput processing. All-inorganic Bragg mirrors with high thermal stability up to 450 °C are prepared via a rapid thermal annealing (RTA) approach, achieving a high ΔRI of 0.67 at 519 nm and up to 0.92 at 380 nm and delivering superior (∼97%) reflectance intensities. We have further fabricated a 11-layer Bragg mirror on a flexible substrate at scales of 5 ft × 0.5 ft using commercial roll-to-roll tools, yielding ∼80% reflectance without RTA, representing unparalleled scalability for flexible, efficient Bragg mirrors by solution processing.