Department of Chemical Engineering and ‡Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH) , Hyoja-dong, Nam-gu, Pohang 790-784, South Korea.
Nano Lett. 2014 Mar 12;14(3):1306-11. doi: 10.1021/nl404281h. Epub 2014 Feb 5.
Size-controlled graphene quantum dots (GQDs) are prepared via amidative cutting of tattered graphite. The power of this method is that the size of the GQDs could be varied from 2 to over 10 nm by simply regulating the amine concentration. The energy gaps in such GQDs are narrowed down with increasing their size, showing colorful photoluminescence from blue to brown. We also reveal the roles of defect sites in photoluminescence, developing long-wavelength emission and reducing exciton lifetime. To assess the viability of the present method, organic light-emitting diodes employing our GQDs as a dopant are first demonstrated with the thorough studies in their energy levels. This is to our best knowledge the first meaningful report on the electroluminescence of GQDs, successfully rendering white light with the external quantum efficiency of ca. 0.1%.
通过对碎石墨的酰胺切割制备了尺寸可控的石墨烯量子点（GQDs）。该方法的强大之处在于，只需调节胺浓度即可将 GQDs 的尺寸从 2nm 调至 10nm 以上。随着尺寸的增加，这些 GQDs 的能隙变窄，呈现出从蓝色到棕色的多彩光致发光。我们还揭示了缺陷在光致发光中的作用，发展了长波长发射并减少了激子寿命。为了评估本方法的可行性，我们首先采用我们的 GQDs 作为掺杂剂的有机发光二极管对其能级进行了深入研究。这是我们所知的关于 GQDs 电致发光的第一个有意义的报告，成功地实现了外量子效率约为 0.1%的白光。
