Roles of nitrogen functionalities in enhancing the excitation-independent green-color photoluminescence of graphene oxide dots

Chiao Yi Teng, Ba Son Nguyen, Te Fu Yeh, Yuh Lang Lee, Shean Jen Chen, Hsisheng Teng

研究成果: Article

9 引文 斯高帕斯(Scopus)

摘要

Fluorescent graphene oxide dots (GODs) are environmentally friendly and biocompatible materials for photoluminescence (PL) applications. In this study, we employed annealing and hydrothermal ammonia treatments at 500 and 140 °C, respectively, to introduce nitrogen functionalities into GODs for enhancing their green-color PL emissions. The hydrothermal treatment preferentially produces pyridinic and amino groups, whereas the annealing treatment produces pyrrolic and amide groups. The hydrothermally treated GODs (A-GODs) present a high conjugation of the nonbonding electrons of nitrogen in pyridinic and amino groups with the aromatic π orbital. This conjugation introduces a nitrogen nonbonding (nN 2p) state 0.3 eV above the oxygen nonbonding state (nO 2p state; the valence band maximum of the GODs). The GODs exhibit excitation-independent green-PL emissions at 530 nm with a maximum quantum yield (QY) of 12% at 470 nm excitation, whereas the A-GODs exhibit a maximum QY of 63%. The transformation of the solvent relaxation-governed π∗ → nO 2p transition in the GODs to the direct π∗ → nN 2p transition in the A-GODs possibly accounts for the substantial QY enhancement in the PL emissions. This study elucidates the role of nitrogen functionalities in the PL emissions of graphitic materials and proposes a strategy for designing the electronic structure to promote the PL performance.

原文English
頁(從 - 到)8256-8265
頁數10
期刊Nanoscale
9
發行號24
DOIs
出版狀態Published - 2017 六月 28

    指紋

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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