Fluorescence Solvatochromism of Carbon Dot Dispersions Prepared from Phenylenediamine and Optimization of Red Emission.,Langmuir

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Fluorescence Solvatochromism of Carbon Dot Dispersions Prepared from Phenylenediamine and Optimization of Red Emission.
Langmuir ( IF 3.7 ) Pub Date : 2019-11-15 , DOI: 10.1021/acs.langmuir.9b02739
Rina Sato ₁ , Yoshiki Iso ₁ , Tetsuhiko Isobe ₁

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Fluorescent carbon dots (CDs) are of interest as a promising alternative to quantum dots, partly because they do not include heavy metals. However, most CDs exhibit blue or green emission, while red-emitting CDs are required for a variety of applications. In the present work, CDs were synthesized by refluxing three phenylenediamine (PD) isomers with amino groups at different positions (o-PD, m-PD, and p-PD) in diphenyl ether at 250 °C for 4 h. Upon dispersing the resulting CDs in eight solvents with different polarities, emission colors ranging from green to red were observed. Among these CDs, p-PD-derived CDs exhibited both the longest emission wavelength range, from 538 to 635 nm, and the highest absolute red photoluminescence quantum yield (PLQY) of 15%. Herein the results are discussed based on a comparison of the polymerization processes of o-PD, m-PD, and p-PD. This work demonstrated that the optimum reaction time was 2 h, which yields a p-PD-derived CD dispersion in methanol with red emission and an absolute PLQY as high as 18%. Additionally, the use of 1-decanol and deuterated methanol in place of methanol improved the maximum absolute PLQY to 25% and 36%, respectively. These improved values are attributed to reduced concentration quenching by suppression of π-π stacking interactions and inhibition of the nonradiative relaxation process through the vibration of OH groups, respectively.

中文翻译：

苯二胺制备的碳点分散体的荧光溶剂变色和红色发射的优化。

荧光碳点（CD）可以作为量子点的有前途的替代品，部分原因是它们不包含重金属。但是，大多数CD都会发出蓝色或绿色的光，而发出红色的CD则需要多种应用。在目前的工作中，CD通过在250°C下于苯醚中回流3个带有不同位置氨基的苯二胺（PD）异构体（o-PD，m-PD和p-PD）合成4小时而合成。将所得CD分散在具有不同极性的八种溶剂中后，观察到从绿色到红色的发射颜色。在这些CD中，源自p-PD的CD既显示出最长的发射波长范围（从538至635 nm），又显示出最高的绝对红色光致发光量子产率（PLQY），为15％。在此，基于对o-PD，m-PD和p-PD的聚合过程的比较来讨论结果。这项工作表明，最佳反应时间为2 h，可在甲醇中产生p-PD衍生的CD分散体，并发出红色光，绝对PLQY高达18％。此外，使用1-癸醇和氘代甲醇代替甲醇可使最大绝对PLQY分别提高到25％和36％。这些改善的值分别归因于通过抑制π-π堆积相互作用和通过抑制OH基团的振动来抑制非辐射弛豫过程，从而降低了浓度猝灭。使用1-癸醇和氘代甲醇代替甲醇可使最大绝对PLQY分别提高到25％和36％。这些改进的值分别归因于通过抑制π-π堆积相互作用和通过抑制OH基团的振动来抑制非辐射弛豫过程，从而降低了浓度猝灭。使用1-癸醇和氘代甲醇代替甲醇可使最大绝对PLQY分别提高到25％和36％。这些改进的值分别归因于通过抑制π-π堆积相互作用和通过抑制OH基团的振动来抑制非辐射弛豫过程，从而降低了浓度猝灭。

更新日期：2019-11-15

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