Sterically Stabilized Carbon Dots as Solid-State Phosphors for White-Light-Emitting Diodes

Solid-state photoluminescence (PL) is highly important for practical optoelectronic applications. However, conventional carbon dots often suffer from fluorescence quenching induced by aggregation in a solid state, limiting their potential applications. In this report, sterically stabilized polymeric carbon dots (PCDs) (<2 nm) are prepared to achieve effective PL emission even in the solid-sate composite using a simple one-step hydrothermal treatment. These PCDs show unique fluorescence properties of tunable PL color change with the concentration covering the visible spectrum range from blue to orange in aqueous solution and the wavelength-dependent broad PL with maximum excitation at around 480 nm in solid-state epoxy composite. Practically applicable "single phosphor on a chip" in white-light-emitting diodes (WLEDs) application is successfully demonstrated by combining our PCDs/epoxy composite with a 460 nm blue-based LED chip, which is longer than most studies on the performance of CD-related white LEDs using UV or deep-blue LED chips as the excitation source. These results suggest that this type of PCDs may not only effectively suppress the aggregation-caused quenching effect in solid matrices but also show enhanced PL properties as a solid-state phosphor for practical white light emission applications.