For practical applications of carbon dots (CDs), a major challenge is to prevent the notorious aggregation-caused quenching (ACQ) effect. Herein, a new type of CDs (CD1) has been developed that can transform from ACQ to an enhancement of fluorescence by aggregation-induced emission (AIE). The blue fluorescence of the CDs is suppressed by ACQ. However, this is accompanied by the phenomenon of AIE at a longer wavelength, resulting in the emergence and gradual enhancement of yellow fluorescence. The obtained CD1 solid powder shows a bright yellow emission with a photoluminescence quantum yield (PLQY) of 65%. The photoluminescence (PL) spectra, absorption spectra, and time-resolved PL decay curves indicate that Förster resonant energy transfer from dispersed CD1 particles to large CD1 agglomerations leads to the enhancement of yellow fluorescence. To exploit its high PLQY and strong AIE, CD1 is applied as a color-converting layer on blue light-emitting diode (LED) chips to fabricate white LEDs (WLEDs). The obtained devices show white light coordinates of (0.29, 0.38) and (0.32, 0.42), which are close to pure white light (0.33, 0.33), and luminous efficiencies of 97.8 and 93.9 lm·W–1 and show good stability. The low cost, easy fabrication, controllability, and favorable fluorescence properties signify that CD1 of AIE will have superior performance in a variety of applications.

Carbon dots (CDs) that exhibit emission over the whole visible spectrum are desired for use in light-emitting diodes (LEDs). Here, CDs displaying tunable fluorescence over the whole visible region are synthesized. Different concentrations of CDs are uniformly dispersed in epoxy resin and coated on 405 nm LED chips to obtain monochrome blue, cyan, green, yellow, red, and deep red LEDs that yield a color gamut covering 99.4% of the National Television Standards Committee (NTSC) standard. These monochrome LEDs display similar high stability. Furthermore, warm and neutral white LEDs are produced by coating cyan- and red-emitting CD layers on 405 nm LED chips, achieving color-rendering indexes (CRIs) of 96.4 and 96.6, respectively. Two fluorescent conversion layers derived from one material at different concentrations simplify the preparation of high-CRI white LEDs. The uniform weak changes of the cyan and red photoluminescence peaks during operation ensure the high stability of these CD-based white LEDs. This research provides a new avenue to develop low-cost, easy-to-prepare CDs with tunable emission colors as alternative phosphors for LED-based high-performance displays and lighting.

Single concentration-dependent carbon dots were synthesized and applied to the rapid identification of eight kinds of pathogenic microorganisms.

Warm white light has been demonstrated using color-tunable Ce3+-activated yellow-green oxyfluoride solid-solution and Eu3+-doped red borate phosphors.