摘要
Graphitic carbon nitride quantum dots(CNQDs) are emerging as attractive photoluminescent(PL)materials with excellent application potential in fluorescence imaging and heavy-metal ion detection. However, three limitations, namely, low quantum yields(QYs), self-quenching,and excitation-dependent PL emission behaviors, severely impede the commercial applications of crystalline CNQDs.Here we address these three challenges by synthesizing borondoped amorphous CNQDs via a hydrothermal process followed by the top±down cutting approach. Structural disorder endows the amorphous boron-doped CNQDs(B-CNQDs)with superior elastic strain performance over a wide range of pH values, thus effectively promoting mass transport and reducing exciton quenching. Boron as a dopant could fine-tune the electronic structure and emission properties of the PL material to achieve excitation-independent emission via the formation of uniform boron states. As a result, the amorphous B-CNQDs show unprecedented fluorescent stability(i.e., no obvious fading after two years) and a high QY of 87.4%;these values indicate that the quantum dots obtained are very promising fluorescent materials. Moreover, the B-CNQDs show bright-blue fluorescence under ultraviolet excitation when applied as ink on commercially available paper and are capable of the selective and sensitive detection of Fe^(2+) and Cd^(2+) in the parts-per-billion range. This work presents a novel avenue and scientific insights on amorphous carbon-based fluorescent materials for photoelectrical devices and sensors.
石墨相氮化碳量子点(CNQDs)作为一种具有吸引力的光致发光(PL)材料,在荧光成像和重金属离子检测方面具有巨大的潜力.然而,晶态CNQDs的商业化应用仍被其低荧光量子产率、自猝灭和激发波长依赖行为所限制.我们提出利用硼掺杂和CNQDs非晶化的协同策略——通过水热和自上而下的超声剥离方法制备非晶态硼掺杂CNQDs(B-CNQDs)——以解决以上三个问题.结构无序赋予了非晶态B-CNQDs大范围pH下优越的弹性应变性能,从而可以有效促进电荷传输,减少激子猝灭.同时,通过形成均匀的硼掺杂表面态,可以巧妙地调节CNQDs的电子结构和荧光发射特性,实现无激发波长依赖行为.结果表明,非晶态B-CNQDs具有优异的荧光稳定性(2年后无明显衰减),且具有87.4%的高量子产率,是非常有前途的荧光材料.在紫外光激发下,B-CNQDs在商业用纸上可以显示出特定图形的亮蓝色荧光.此外,B-CNQDs对Fe^(2+)和Cd^(2+)在ppb检测范围内具有高度的选择性和灵敏度.本工作可为开发具有高稳定性和高量子产率的非晶态碳基荧光材料用于光电器件和传感器提供实验基础和有益启示.
作者
Bo Li
Jing Zhang
Ziyu Luo
Xinpei Duan
Wei-Qing Huang
Wangyu Hu
Anlian Pan
Lei Liao
Lang Jiang
Gui-Fang Huang
李波;张静;骆子煜;段鑫沛;黄维清;胡望宇;潘安练;廖蕾;江浪;黄桂芳(College of Physics and Electronics and College of Materials Science and Engineering,Hunan University,Changsha 410082,China;Institute of Chemistry,Chinese Academy of Sciences,Beijing 100049,China;Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education&Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices,College of Physics and Electronics,Hunan University,Changsha 410082,China)
基金
supported by the National Natural Science Foundation of China (51772085 and 12072110)
the Natural Science Foundation of Hunan Province (2020JJ4190)。
