Dual-mode photochromic luminescence of carbon dots induced by photoinduced electron transfer

The integration of photochromism and photoluminescence in functional materials presents significant challenges, particularly in achieving broad-spectrum color modulation and rapid response. In this work, we have developed sodium-doped and sodium/boron co-doped CDs that exhibit dual-mode photochromic luminescent behavior through a novel radical-mediated mechanism. The Na-CDs demonstrated a 180 nm red-shift in emission, transitioning from 450 to 630 nm. The Na, B-CDs achieved blue-shifted, multicolor emission, progressing from orange to yellow and green under 30-s UV irradiation. Notably, the photochromic states spontaneously reverted to their initial configurations without external stimuli. These phenomena arise from photoinduced electron transfer between pristine CDs and light-generated anionic radicals. Leveraging these unique photochromic properties, we implemented reversible anti-counter-feiting systems and information encryption platforms. Furthermore, the photochromic CDs exhibit daylight-responsive UV detection capabilities and are functional in plant cell imaging, significantly expanding their potential applications in optoelectronic devices.