Hot electrons in carbon nitride with ultralong lifetime and their application in reversible dynamic color displays

Abstract

Plasmonic colors enabled by resonant hot electrons offer unique advantages in imaging, display, and optical encryption applications. Although metasurfaces can show full colors with sub-wavelength spatial resolutions, it is challenging for them to generate dynamic colors. Herein, we report an approach to dynamically control the color of semiconducting nanoparticles with plasmonic properties by tuning their hot-electron lifetime from timescales of seconds to days. The color switch is realized by storing photogenerated electrons, which produce plasmons upon light excitation, in carbon nitride. A photochromic display based on long-lived hot electrons is demonstrated. Two-dimensional patterns with unlimited designs and feature sizes from micro- to macro-scale are generated through laser writing or photolithography and then can be erased by exposure to moisture or heat, hundreds of times without obvious destruction to the device. This work may expand the possibilities of using hot electrons for reversibly manipulating the colors of semiconductor nanoparticles with plasmonic properties. • C 3 N 4 -based paper can change color upon UV illumination or heat/moisture • Photochromic paper stores hot electrons and holes in air for up to 5 days • Hot electron-induced surface plasmon is responsible for photochromism • Photochromic paper is demonstrated for color displays and security labels It is challenging to achieve photochromism in semiconductor systems by photodoping under aerobic environments. Cheng et al. develop paper consisting of carbon nitride and cellulose that shows reversible color change upon photodoping or heat/moisture in air. Its photochromic mechanism is unveiled, and application for display and anti-counterfeiting is demonstrated.