One-pot synthesis of single-component graphene quantum dots for stable and bright white luminescence films as a phosphor

Graphene quantum dots (GQDs) with the merits of low cost, non-toxicity and unique optical properties have attracted much attention in various fields. However, it is still challenging to synthesize one-component white-light emissive GQDs with high photoluminescence quantum yield (PLQY). In this work, 1,5-diaminonaphthalene (1,5-DAN) and tartaric acid (TA) were smartly introduced as the precursors in a solvothermal reaction. As a matter of fact, the obtained GQDs exhibited a blue-emission band centered at 413 nm (surface state emission) and a yellow-green-emission band at 558 nm (core-state emission) might be originated from various surface functional groups and inner π-conjugated structure, respectively, which enabled white luminescence of the GQDs. It reveals that both of 1,5-DAN and TA played a vital role on forming the yellow-green-emission band by providing the components of benzene rings and C[dbnd]C/C[dbnd]O bonds, respectively. Moreover, the white-light emissive GQDs (W-GQDs) with the mean size of ∼2.7 nm exhibited a PLQY as high as 28.68% and good photostability under the 365 nm UV light and daylight. A PLQY up to 9.32% can still be achieved in the solid GQDs/polyvinyl alcohol film. Therefore, our prepared GQDs are promising for white light emitting diodes application.