High-performance carbon quantum dots with tunable emission wavelength and intensity via diarylethene coupling

Journal article, 2026

Achieving precise and reversible modulation of both photoluminescence (PL) wavelength and intensity in carbon-based nanomaterials is critical for developing next-generation smart sensors and optoelectronic devices. Herein, we report a robust dual-mode PL modulation system based on high-performance carbon quantum dots (CQDs) and diarylethene (DAE) photoswitches. The synthesized CQDs possess an ultra-high photoluminescence quantum yield (PLQY) of 93.1%, attributed to the dominant surface C–O functional groups minimizing non-radiative recombination. We demonstrate that the PL emission wavelength of these CQDs can be continuously tuned from 420 to 500 nm by manipulating the intramolecular charge transfer (ICT) effect via solvent polarity or inducing controlled aggregation states. Furthermore, by coupling with DAE photoswitches, the PL intensity can be reversibly toggled on and off with a high quenching efficiency of 88.2%, governed by the photoisomerization of DAE and the inner filter effect. Crucially, this tunable emission color and reversible intensity switching are successfully translated to solid-state polymethyl methacrylate (PMMA) films, enabling reversible writing and erasing of different patterns. This work presents heavy-metal-free, high-efficiency carbon-based materials with versatile optical tunability, offering new insights into the functional engineering of CQDs for intelligent nanotechnology and optoelectrical applications.