jp7b08039_si_001.pdf (2.94 MB)
Carbon Dots from a Single Source Exhibiting Tunable Luminescent Colors through the Modification of Surface Functional Groups in ORMOSIL Films
journal contribution
posted on 2017-11-29, 00:00 authored by Dipsikha Bhattacharya, Manish Kumar Mishra, Goutam DeA simple strategy
to fabricate carbon dots (CDs) incorporated organically
modified silica (ORMOSIL) films exhibiting tunable tricolor emission
has been accomplished. First, the green-emitting CDs with excitation-independent
nature and high quantum yield were prepared from o-phenylenediamine in ethanol by solvothermal method. These CDs after
purification were dispersed in ORMOSIL sol, and their photoluminescence
wavelengths were tuned to three intense luminescent colors (orange,
yellow, and green) by adjusting the pH of the sol. It was observed
that with pH tuning the functional groups residing on surface-passivated
CDs are undergoing chemical modifications, and accordingly the PL
emission of CDs in ORMOSIL sol systematically changes to orange, yellow,
and green emissions, respectively. Interestingly, the structure of
such surface-modified CDs can be well-preserved in the ORMOSIL film-matrix
with substantial concentration to obtain the above tricolor luminescent
films on glass. A systematic X-ray photoelectron spectroscopy study
revealed that the blue shifting in triluminous films (from 560 to
510 nm) with pH increment was originated due to the deprotonation
of the surface groups (−CONH– → −CO(N–)–; −NH3+ →
−NH2) associated with the CDs. The plausible mechanism
behind the rationalization of pH-triggered engineering of surface-passivated
CD-ORMOSIL sols and their confinement in films has been explored.