Rational Design of Angle-Resilient Ultrathin Metals With Broadband Visible–Near-Infrared Transparency

Transparent conductors are critical for optoelectronic devices such as photodetectors and solar cells. Ultrathin metals, particularly silver, are widely used due to their excellent optoelectrical properties and large-scale processability. However, their inherently high extinction coefficients limit transmittance to below 40% even for high-quality films, with further losses at oblique angles, significantly restricting real applications. To address these limitations, we propose a universal design strategy for broadband anti-reflection based on wavelength- and angle-insensitive phase modulation. This method enables the design of corresponding dielectric layers for various ultrathin metals and different spectral regions, thereby effectively suppressing optical reflection in ultrathin metals. Simulation results and experimental validation demonstrate that the average transmittance of ultrathin silver films can be relatively improved by over 80% across the visible to infrared spectra, under incident angles up to ±45°. As a proof of concept, the rational design of ultrathin silver films with the above approach was developed for various applications. When integrated into a Bi₂O₂Se photodetector, the transparent electrode suppressed the dark current by ∼50% while simultaneously enhancing the photocurrent and response speed, highlighting the potential for multispectral optoelectronic devices and next-generation photovoltaics.