Reaction-time-controlled carbon dots nanoarchitectonics with stable and bright photoluminescence for white light emission

It is still a challenge for multicolor carbon dots (CDs) with stable and bright photoluminescence (PL). The controlling of synthesis becomes a hot topic. In this paper, CDs with blue-, green- and red-emitting named as B-CDs, G-CDs, and R-CDs were prepared using three isomers of phenylenediamine as precursors by one-step solvothermal synthesis . Green and red emitting CDs with C, N and O components named as samples G-CDs and R-CDs revealed uniform nanoparticle distribution with average sizes of 7.2 and 5.7 nm, respectively. The PL peak wavelength of three kinds of CDs were 430, 546 and 613 nm, and their average fluorescence lifetime was 5.32, 22.35, 8.74 ns, respectively. The full width at half maximum of PL spectra of the samples was 65.12, 92.63, 83.62 nm, and their PL quantum yields were 8.19, 43.43, and 5.14%, respectively. The brightly luminescent CDs were further embedded in prepared polyvinyl alcohol films to prepare a white emitting layer by adjusting the ratios of CDs with different emitting color. The composite CDs revealed stable and bright white emitting in the film with a Commission Internationale d'Eclairage (CIE) coordinate of (0.28, 0.33). The result suggested that these unique luminescent CDs have potential applications in various luminescence fields.