碳量子点在白光发光二极管中的应用进展
Recent Progress in the Application of Carbon Quantum Dots in White-Light-Emitting Diodes
DOI: 10.12677/MS.2022.125052, PDF, 下载: 30  浏览: 46  国家自然科学基金支持
作者: 杨雨虹, 许家凤, 王 林:锦州医科大学食品科学与工程学院,辽宁 锦州;张 杰, 常晓杰*, 周西斌*:锦州医科大学药学院,辽宁 锦州;金红梅:锦州医科大学畜牧兽医学院,辽宁 锦州
关键词: 碳量子点荧光发光二极管白光发光二极管Carbon Quantum Dots Fluorescence Light Emitting Diode White Light Emitting Diodes
摘要: 白光发光二极管(WLED)具有能量效率高、工作寿命长、功耗低等优点,多年来受到了学者的广泛重视。目前,大多数商业WLED是使用传统的稀土基荧光粉来构建的。碳量子点(CDs)是一类有吸引力的纳米材料,它具有生物相容性、良好的水溶性、生态友好性、低毒性和光稳定性,最近在生物及光电领域的应用被广泛开发和研究。碳点的电子结构以及光学转换效率可以在很宽的光谱范围内被控制和调整,所以CDs应用在WLED正在受到广泛的重视。本文总结了最近碳量子点在构建WLED方面的进展。
Abstract: White light emitting diodes (WLEDs) have the advantages of high energy efficiency, long working life and low power consumption, and have been widely studied by scholars for many years. Currently, most commercial WLEDs are constructed using traditional rare-earth-based phosphors. Carbon quantum dots (CDs), an attractive class of nanomaterials with biocompatibility, good water solubility, eco-friendliness, low toxicity, and photostability, have recently been widely developed for bio- and opto-electronic applications. The electronic structure and optical conversion efficiency of carbon dots can be controlled and tuned in a wide spectral range, so the application of CDs in WLEDs is receiving extensive attention. We summarize the recent progress of carbon quantum dots in constructing WLEDs.
文章引用:杨雨虹, 张杰, 金红梅, 许家凤, 王林, 常晓杰, 周西斌. 碳量子点在白光发光二极管中的应用进展[J]. 材料科学, 2022, 12(5): 500-509. https://doi.org/10.12677/MS.2022.125052

1. 引言

发光二极管(LED)与传统灯具相比,LED灯具有节能、寿命长、响应速度快、不含重金属等优点。日常照明最常用的是白光LED (WLED),具有无频闪、光谱可微调、光线柔和等特点,目前已基本代替白炽灯和日光灯走进了千家万户。主流的WLED使用稀土材料或半导体量子点作为荧光粉,存在成本高、有健康风险等问题 [1]。为了解决这些问题,在近十几年里,研究人员不断在寻找各种替代材料。

近年来,碳量子点(CDs)作为一种新型的零维荧光碳基纳米材料,因为具有出色的发光性能、良好的生物相容性、光稳定性和能量转换能力,且不会产生内在毒性等特点,广泛应用在了生物成像、纳米医学、药物输送、太阳能电池、发光二极管、光催化、电催化和其他相关领域 [2]。碳量子点的制备方法简单,原料来源丰富,且价格低廉 [3]。碳量子点的制备分为自上而下和自下而上两种方法。自上而下的方法是基于将大块部件分解成更小的部分,涉及的方法有电化学降解、纳米光刻、电化学和酸性氧化、电弧放电、激光烧蚀和化学剥离。自下而上的方法是由较小的单元生成较大的目标物,涉及的方法包括微波法、水热法、自热法、超声法等 [2]。与具有狭窄发射带宽的商业稀土荧光粉和传统的半导体QDs相比,大部分CDs具有宽波长发射特性(全峰宽最大值>80纳米),这是由于其强大的电子–声子耦合,以及高度分散的颗粒尺寸,这就使得CDs成为构建WLED的合适材料 [4]。另外,CDs由于表面存在各种官能团(−OH、−COOH、−NH2等),通过一系列的化学处理,CDs拥有与有机和无机分子结合的强大能力,从而实现对其光学性质的进一步改进和优化。基于CDs的LED主要有两种类型:光致发光型和电致发光型 [5]。第一种类型可以很容易地通过将CDs沉积到作为激发源的商用紫外或蓝光发光芯片上而产生;在电致发光类型中,CDs作为一个活性层,通过外加电场的电荷注入而产生电致发光,一般情况下,这比生产光致发光型的LED要复杂得多。

本文系统地总结了近年来碳量子点构建WLED的方法,并按照荧光单元的组成成分将这些工作分为两类,第一类是利用纯碳量子点构建WLED的相关工作,第二类是将碳量子点与其他材料复合构建WLED的研究工作,下面详细介绍这些工作。

2. 纯碳点构建WLED

WLED可由合成的蓝、绿、红光三色碳量子点复合后置于商用紫外芯片或电致发光单元上构建,也可由绿、红光双色碳量子点复合后置于商用蓝光芯片或电致发光单元上制备,也有学者将蓝光和黄光双色碳量子点复合后制备偏冷色WLED。

Chen [6] 等以没食子酸和邻苯二甲醛为原料,通过溶剂热法制备了红、绿和蓝色发光CDs,经复合后制备了具有CIE色度坐标(0.32, 0.34)的WLED。Li [7] 等以单宁酸和邻、间、对苯二甲醛为碳源,采用溶剂热法成功制备了多色发光CDs,之后混合制备了WLED。Chen [8] 等报告通过N-乙酰半胱氨酸的一步热解合成产CDs,所制备的CDs粒径范围为3~5 nm,在蓝光的激发下,CDs会发出广泛的黄色荧光。通过将发黄光的CDs与蓝色GaN基LED芯片相结合,开发了一种构建WLED的经济方法。Yang [9] 等以柠檬酸为碳源,硫脲和氟化铵为掺杂剂源,N,N-二甲基甲酰胺为溶剂,成功制备了最大发射波长为714 nm的CDs。量子产率高达22.64%。制备的CDs在氧气存在下会自氧化,导致其发射蓝移,可以在不添加其他荧光物质的情况下直接用于制备WLED。Han [10] 等以1,4-苯二异氰酸酯为原料,采用溶剂热法制备了红色碳量子点,并与绿色碳量子点混合,在蓝色芯片上制备了WLED。Chen [11] 等以2,7-二羟基萘为碳源,N,N-二甲基甲酰胺为氮源,合成了宽双峰发射光谱的氮掺杂CDs,经硅烷偶联剂固化后直接制得暖白色LED。Davi [12] 等使用丹磺酰氯、对苯二氨基苯醚和对苯二胺作为前体,通过水热法合成了具有蓝色(C-DsCl)、绿色(C-pPDDS)和红色(C-pPD)三色发射的碳点,并制备了WLED。Li [13] 等利用邻苯二胺和三(羟甲基)氨基甲烷在硫酸–水220度10小时条件下,得到用于白色发光二极管的明亮三色发射碳点。Lei [14] 等以邻苯二胺和苯丙氨酸为原料,采用不同溶剂的溶剂热法制备了多色荧光CDs。具体来说,对于蓝色碳点是将邻苯二胺和苯丙氨酸溶解在甲酰胺中合成的;对于绿色碳点,是将邻苯二胺和苯丙氨酸溶解在N,N-二甲基乙酰胺中合成的;对于红色碳点,是将邻苯二胺和苯丙氨酸溶解在水–硫酸中合成的。Liu [15] 等通过溶剂热法从甲苯二酸和邻苯二胺中获得了多色发光CDs。合成R-CDs所用溶剂稀硫酸,Y-CDs所用溶剂为乙醇,B-CDs所用溶剂为甲酰胺。Lyu [16] 等通过热驱动高级氧化工艺,轻松、克级和环保地合成多色石墨烯量子点。他们将氧化石墨烯与间苯二胺、乙二胺、邻苯二胺和对苯二胺混合,水热法制备了蓝、绿、黄、橙、红色碳点。Meng [17] 等将对苯二甲醛和对苯二乙腈溶解在水中,加催化量的NaOH,并在120℃ 1小时、140℃ 1.5小时和160℃下加热/超声处理2小时以分别得到红色、绿色、蓝色固态带隙荧光碳量子环的克级合成,最终经过复合制备了明亮的WLED。Song等 [18] 通过水热法制备多色荧光CD。他们将柠檬酸和尿素在剧烈搅拌下以不同的比例混合到不同的溶剂(水、乙醇和DMF)中,然后将水热反应器中的溶液分别在160℃/180℃加热6小时/10小时,得到CDs溶液,并制得白光LED。Su等 [19] 通过使用不同摩尔比的对苯二胺与ZnCl2在乙醇中200℃的温度下合成颜色可调的Zn掺杂CDs。通过调整对苯二胺与ZnCl2的比例(1:0、1:0.1、1:0.5),可以合成不同发光颜色的Zn掺杂CDs。Wang等 [20] 通过一步微波法以间苯三酚和尿素为碳源,通过调节反应物比例和微波功率制备的CDs的最大发射波长逐渐从445 nm转移到643 nm,得到具有蓝色、绿色、黄色、橙色和红色发射的五种典型CDs,实现了抗自猝灭固态荧光CDs。它表现出可调谐的全色固态发射,无需任何其他额外的固体基质。Zhu等 [21] 通过使用多种苯二酚和氧化剂作为前体,通过乙醇介导的溶剂热法成功地制备了无定形CDs,并且通过调整苯酚和氧化剂的组合来调整CDs的发射颜色。得到蓝、绿、黄、红CDs。Jin等 [22] 开发了一种绿色水热法,使用L-酪氨酸(用于蓝色CDs)、邻苯二胺(用于绿色CDs)和L-酪氨酸/邻苯二胺混合物(用于橙红色CDs)来获得WLED的三种发射颜色。Dang等 [23] 首先使用低聚物聚酰胺树脂作为碳源制备CDs,通过一步超声在室温下得到发射白色荧光的碳点,之后通过添加硅烷偶联剂,将白色荧光CDs的量子产率从3.3%进一步提高到28.3%,并使用这些碳点作为光转换材料成功地制备了白光发光二极管。Li等 [24] 使用1,5-二氨基萘作为前体,三氯甲烷作为氯源,通过调节反应条件(例如温度、乙醇和水的比例),其CDs的最佳量子产率高达34%。Ding等 [25] 在KCl催化下,采用无溶剂法加热邻苯二胺,获得了一系列具有442~621 nm荧光发射可调、量子产率为23%~56%、产率在34%~72%以内的CDs。Dong等 [26] 将氧化石墨烯通过NaBH4还原,制备成白光碳点。Feng等 [27] 通过简单的一步水热处理葡萄糖作为碳源和PEG200作为钝化剂制备构建WLED的碳量子点。Liu等 [28] 将柠檬酸和硅烷偶联剂分别用作碳源和表面涂层剂,合成了光致发光量子产率为22.5%的单组分白光发射固态碳微球,基于固态碳微球单组分白色荧光粉的WLED具有良好的颜色稳定性。表1是上述工作的总结,比较了他们的碳源、合成方法、颜色、碳点分离方法以及构建WLED所用的分散剂。

Table 1. Carbon source, preparation, color, separation method and hardener for WLEDs entirely based on CDs

表1. 完全基于碳量子点的白光发光二极管所用的碳源、制备方法、颜色、分离方法和固化剂

虽然纯碳点构建的WLED已经取得了一定的成功,但是由于目前碳量子点量子产率较低(尤其是红光的量子产率低),一般商用的LED均会用量子产率高的稀土化合物代替其中一种或几种量子产率低的组分,以期达到更高的发光效率。但是不含对环境有害的稀土元素的LED仍然是未来发展的总体方向和目标。

3. 碳点与其他组分复合构建WLED

一些研究人员合成出单色碳量子点(尤其是红色碳量子点),可以与其他无机或有机染料混合来制备WLED;由于CDs表面存在各种官能团(−OH、−COOH、−NH2等),CDs拥有与有机和无机分子结合的强大能力,从而实现对其光学性质的进一步改进和优化。将碳量子点与SiO2、金属有机框架(MOF)、无机盐等材料复合,能够显著降低CDs由π-π堆积电子非辐射跃迁作用引起的自淬灭作用,进一步提升发光性能。

He等 [29] 以番红T和柠檬酸为前驱体,采用一步水热法制备红光碳点;改CDs与蓝色和绿色稀土配合物可以组合制成WLED。Chen等 [30] 以对苯二胺为碳源,通过溶剂热法合成了红色荧光碳点并制成PVA膜,通过与黄色荧光粉膜叠合,在蓝色芯片激发下得到暖白光。Zheng等 [31] 以马铃薯淀粉为碳源,通过微波辅助水热法实现了一种简单、绿色的荧光碳点合成。通过在220摄氏度下对淀粉溶液进行水热处理,制备了最大量子产率为2.46%的CDs。另外他们以淀粉和乙二胺为碳源和氮源,在相同条件下获得了氮掺杂CDs (N-CDs),其量子产率是未掺杂CDs的两倍。CDs和N-CDs均表现出优异的水溶性和良好的热稳定性,在紫外光下发出蓝色荧光,但后者的荧光强度明显高于前者。使用CDs/淀粉复合材料和N-CDs作为荧光粉的两个白光发光二极管发出黄白光和白光。Li等 [32] 报告了一种简便的等离子体诱导方法,可以在几分钟内使用丙烯酰胺作为前体制造光致发光碳点。之后他们将CDs作为颜色转换器与CDs Te量子点混合,使用UV-LED芯片作为激发光源来生成白光LED。Cheng等 [33] 通过静电组装方法制备了具有高导热率的白色发光碳点/氮化硼纳米片(BNNS)杂化纳米结构。在掺入导热BNNS后,复合材料的热淬火显着降低。C-dots/BNNS杂化荧光粉表现出优异的热和光学性能。Deodanes等 [34] 用石墨烯碳量子点溶液/结晶聚酯树脂基质的混合物涂覆在CDs QDs溶液/结晶聚酯树脂之外,制备了白光发光LED。Fang等 [35] 通过溶胶–凝胶法,将青色荧光碳量子点与铕络合物在二脲丙基三乙氧基硅烷中分散交联,制备了具有增强热稳定性和高效白光的LED。Gao等 [36] 将表面修饰了N-(β-氨基乙基)-γ-氨基丙基甲基二甲氧基硅烷(AEAPMS)的高量子产率、发蓝光、无毒的荧光纳米材料碳点和发橙光的CsPb0.81Mn0.19Cl3的钙钛矿纳米晶体相结合,以制造WLED,所制造的WLED在电流增加和长期工作稳定性方面表现出良好的颜色稳定性。Han等 [37] 使用聚乙烯亚胺(PEI)、磷酸和乙醇作为原料,合成表面含有丰富PEI链的无定形CDs。PEI链可适当分离单个碳核并防止直接的π-π相互作用,克服了聚集过程中的自猝灭,并在没有基质的情况下发明亮的蓝色荧光。在与发红光的铕金属有机框架相结合后,他们成功构建出WLED。He等 [38] 以中性红和硫脲为原料,制备了一种新型黄光碳点(CDs)水溶液,之后将CDs与Al-MOFs和Zn-MOFs复合制备成CDs@Al-MOFs和CDs@Zn-MOFs复合材料。两种材料以一定比例用AB胶混合后与蓝光LED芯片组合制备了高显色白光LED。Huang等 [39] 将蓝色发射和绿色发射的碳点与红色发射的Ag-In-Zn-S (AIZS)纳米粒子相结合,构建了一种出色的高显色指数WLED器件。Li等 [40] 用邻苯二胺和L-抗坏血酸合成了蓝色碳量子点,之后与ZnO量子点复合,制备成WLED的碳点/ZnO量子点复合基荧光粉。Liang等 [41] 将碳点作为异相成核的种子,将它们封装成氯化钡晶体,重结晶氯化钡晶体中的碳点被很好地分离,从而抑制了聚集碳点之间的非辐射电子–电子能量相互作用。Lin等 [42] 将CDs结合到AIS@SiO2 QDs表面,合成了具有白光发射的Ag-In-S/ZnS@SiO2-Carbon量子点(AIS-CDs)纳米复合材料,成功克服了传统方法引起的CDs猝灭效应,形成了稳定高效的白色发光二极管用碳量子点纳米复合材料Liu等 [43] 将N-CDs和ZnO QDs相互连接形成碳-ZnO交替量子点链(CZA-QDCs),克服了N-CDs的聚集诱导淬灭效应,从而确保了WLED的高效全光谱荧光。Lu等 [44] 将绿光碳量子点和发红光的罗丹明B (RhB)分子封装到多孔ZIF-8中,获得发黄光的复合材料。通过在商用蓝色(460 nm) LED芯片上涂覆CDs@ZIF-8@RhB@ZIF-8纳米复合材料,可以制成明亮的白光源。

Sun等 [45] 将蓝光CDs、绿色PDs、红色PDs用PVP包覆,再将三者用硅酮混合,制备了白色发光LED。Sun等 [46] 将蓝色发射碳点与绿色和红色发射锌铜铟硫化物(ZCIS)核/壳量子点(QD)相结合,以实现具有93的高显色指数的WLED。Wang等 [47] 将碳点与Zr(iv)-MOF复合,通过在商用UV-LED芯片上沉积CDs/Zr-MOF纳米复合材料构建了高显色指数的WLED。Wang等 [48] 一锅法,将蓝色碳点和黄色Zr(iv)-MOF复合,制备了冷暖可调的白光LED。Zhang等 [49] 通过将蓝色/绿色发光的N掺杂碳点嵌入二氧化硅纳米球中来实现高发光无稀土复合粉末。通过将蓝色/绿色CDs@SiO2和红色CDsTe@CaCO3复合材料与NUV芯片相结合,制造了具有良好性能的白色LED。Zhang [50] 等通过将黄色发光碳点与金纳米颗粒耦合后,增强了荧光强度,使其向白色LED方向强烈增强。Chen等 [51] 通过水热法从柠檬酸和APTES合成硅烷官能化的蓝色荧光CDs,之后与由(3-巯基丙基)三甲氧基硅烷(MPTMS)改性的发黄光CDs NC共水解,合成了在紫外激发下发射明亮白光的二氧化硅基CDs/CDs NC杂化物。

Table 2. Carbon source, dopant, preparation, CDs color, separation method and hardener used in the construction of WLEDs by doping CDs with other components

表2. 碳量子点掺杂其他组分构建白光发光二极管所用的碳源、掺杂剂、制备方法、碳点颜色、分离方法和固化剂

表2所述,单一发光碳点可以选择与其他稀土化合物、钙钛矿、MOF材料等发光材料复合构建WLED,这样的好处是其他发光材料来源广泛,成熟且量子产率较高,能够使构建的WLED发光效率较高。目前虽然目前存在多种方法,如将碳点分散在SiO2、MOF中进行钝化等,但目前存在的问题依然是红光碳量子点的荧光产率较低,导致WLED整体效率不高,所以今后研究的重点方向是高量子产率,高稳定性的红光碳量子点开发。

4. 总结

目前,CDs在光电子学领域的应用具有很大的发展潜力。除了公认的CDs作为廉价、无毒、环境友好的材料的优势外,丰富的合成方法为制备具有所需光学和电学特性的CDs提供了无限可能。由于CDs的制造简单,而且基于CDs的固态复合材料具有多种光谱特性,因此在光致发光LED中使用CDs作为荧光粉已被证明是一个有前景的方向。在此我们总结了最近的相关工作,旨在获得通过纯碳点或通过碳点与掺杂剂共同构建WLED的通用方法。总之,这篇综述对研究合成不同发光特性CDs的学者以及对从事通过掺杂来提升CDs发光性能的开发人员都有一定的帮助。

基金项目

感谢国家自然科学基金项目批准号:21405069;辽宁省“兴辽英才计划”XLYC2007140;大学生创新创业项目《高色纯度高量子产率碳点的合成及应用研究》,20201016094;辽宁省自然科学基金,201602339;辽宁省高等学校优秀人才支持计划,LJQ2015068对本文章的支持。

NOTES

*通讯作者。

参考文献

[1] Wang, A.W., Hou, Y.L., Kang, F.W., Lyu, F.C., Xiong, Y., Chen, W.C., Lee, C.S., Xu, Z.T., Rogach, A.L., Lu, J. and Li, Y.Y. (2019) Rare Earth- Free Composites of Carbon Dots/Metal-Organic Frameworks as White Light Emitting Phosphors. Journal of Materials Chemistry C, 7, 2207-2211.
https://doi.org/10.1039/c8tc04171g
[2] Kumar, P., Dua, S., Kaur, R., Kumar, M. and Bhatt, G. (2022) A Review on Advancements in Carbon Quantum Dots and Their Application in Photovoltaics. RSC Advances, 12, 4714-4759.
https://doi.org/10.1039/d1ra08452f
[3] Bhandari, S., Mondal, D., Nataraj, S.K. and Balakrishna, R.G. (2019) Biomolecule-Derived Quantum Dots for Sustainable Optoelectronics. Nanoscale Advances, 1, 913-936.
https://doi.org/10.1039/C8NA00332G
[4] He, P., Shi, Y., Meng, T., Yuan, T., Li, Y., Li, X., Zhang, Y., Fan, L. and Yang, S. (2020) Recent Advances in White Light-Emitting Diodes of Carbon Quantum Dots. Nanoscale, 12, 4826-4832.
https://doi.org/10.1039/c9nr10958g
[5] Su, L., Zhang, X., Zhang, Y. and Rogach, A.L. (2017) Recent Progress in Quantum Dot Based White Light-Emitting Devices. In: Credi A., Ed., Photoactive Semiconductor Nanocrystal Quantum Dots: Fundamentals and Applications. Springer International Publishing, Cham, 123-147.
https://doi.org/10.1007/978-3-319-51192-4_6
[6] Chen, M., Liu, C., An, Y., Li, Y., Zheng, Y., Tian, H., Shi, R., He, X. and Lin, X. (2021) Red, Green, and Blue Light-Emitting Carbon Dots Prepared from Gallic Acid for White Light-Emitting Diode Applications. Nanoscale ADVANCES, 4, 14-18.
https://doi.org/10.1039/d1na00730k
[7] Li, Y., Liu, C., An, Y., Chen, M., Zheng, Y., Tian, H., Shi, R., He, X. and Lin, X. (2021) Synthesis of Color-Tunable Tannic Acid-Based Carbon Dots for Multicolor/White Light-Emitting Diodes. New Journal of Chemistry, 45, 22559- 22563.
https://doi.org/10.1039/d1nj04393e
[8] Chen, Q.L., Wang, C.F. and Chen, S. (2013) One-Step Synthesis of Yellow-Emitting Carbogenic Dots toward White Light-Emitting Diodes. Journal of Materials Science, 48, 2352-2357.
https://doi.org/10.1007/s10853-012-7016-8
[9] Yang, X., Sui, L., Wang, B., Zhang, Y., Tang, Z., Yang, B. and Lu, S. (2021) Red-Emitting, Self-Oxidizing Carbon Dots for the Preparation of White LEDs with Super-High Color Rendering Index. Science China Chemistry, 64, 1547- 1553.
https://doi.org/10.1007/s11426-021-1033-6
[10] Han, Z., Wang, K., Du, F., Yin, Z., Xie, Z. and Zhou, S. (2018) High Efficiency Red Emission Carbon Dots Based on Phenylene Diisocyanate for Trichromatic White and Red LEDs. Journal of Materials Chemistry C, 6, 9631-9635.
https://doi.org/10.1039/c8tc03497d
[11] Chen, L., Zheng, J., Du, Q., Yang, Y., Liu, X. and Xu, B. (2020) Orange-Emissive Carbon Dot Phosphors for Warm White Light-Emitting Diodes with High Color Rendering Index. Optical Materials, 109, Article ID: 110346.
https://doi.org/10.1016/j.optmat.2020.110346
[12] Davi, L.B.O., Lima, D.J.P. and Barbosa, C.D.A.E.S. (2021) Synthesis and Modulation of Multicolor Fluorescent Carbon Dots from P-Phenylenediamine and Dansyl Derivative for White Light Emitting Diodes. Optical Materials, 121, Article ID: 111502.
https://doi.org/10.1016/j.optmat.2021.111502
[13] Li, X., Wang, Z., Liu, Y., Zhang, W., Zhu, C. and Meng, X. (2020) Bright Tricolor Ultrabroad-Band Emission Carbon Dots for White Light-Emitting Diodes with a 96.5 High Color Rendering Index. Journal of Materials Chemistry C, 8, 1286-1291.
https://doi.org/10.1039/c9tc06187h
[14] Lei, X., Li, D., Chen, Y., Liu, Q., Yan, Q., Wang, J., Han, B., He, G. and An, B. (2022) RGB-Multicolor Fluorescent Carbon Dots by Changing the Reaction Solvent Type for White Light-Emitting Diodes. New Journal of Chemistry, 46, 4979-4982.
https://doi.org/10.1039/d1nj05981e
[15] Liu, Y., Zhang, M., Wu, Y., Zhang, R., Cao, Y., Xu, X., Chen, X., Cai, L. and Xu, Q. (2019) Multicolor Tunable Highly Luminescent Carbon Dots for Remote Force Measurement and White Light Emitting Diodes. Chemical Communications, 55, 12164-12167.
https://doi.org/10.1039/c9cc05581a
[16] Lyu, B., Li, H.J., Xue, F., Sai, L., Gui, B., Qian, D., Wang, X. and Yang, J. (2020) Facile, Gram-Scale and Eco- Friendly Synthesis of Multi-Color Graphene Quantum Dots by Thermal-Driven Advanced Oxidation Process. Chemical Engineering Journal, 388, Article ID: 124285.
https://doi.org/10.1016/j.cej.2020.124285
[17] Meng, T., Wang, Z., Yuan, T., Li, X., Li, Y., Zhang, Y. and Fan, L. (2021) Gram-Scale Synthesis of Highly Efficient Rare-Earth-Element-Free Red/Green/Blue Solid-State Bandgap Fluorescent Carbon Quantum Rings for White Light-Emitting Diodes. Angewandte Chemie International Edition, 60, 16343-16348.
https://doi.org/10.1002/anie.202103361
[18] Song, X., Guo, Q., Cai, Z., Qiu, J. and Dong, G. (2019) Synthesis of Multi-Color Fluorescent Carbon Quantum Dots and Solid State CQDs@SiO2 Nanophosphors for Light-Emitting Devices. Ceramics International, 45, 17387-17394.
https://doi.org/10.1016/j.ceramint.2019.05.299
[19] Su, R., Guan, Q., Cai, W., Yang, W., Xu, Q., Guo, Y., Zhang, L., Fei, L. and Xu, M. (2019) Multi-Color Carbon Dots for White Light-Emitting Diodes. RSC Advances, 9, 9700-9708.
https://doi.org/10.1039/c8ra09868a
[20] Wang, J., Zheng, J., Yang, Y., Liu, X., Qiu, J. and Tian, Y. (2022) Tunable Full-Color Solid-State Fluorescent Carbon Dots for Light Emitting Diodes. Carbon, 190, 22-31.
https://doi.org/10.1016/j.carbon.2022.01.001
[21] Zhu, W., Meng, X., Li, H., He, F., Wang, L., Xu, H., Huang, Y., Zhang, W., Fang, X. and Ding, T. (2019) Ethanothermal Synthesis of Phenol-Derived Carbon Dots with Multiple Color Emission via a Versatile Oxidation Strategy. Optical Materials, 88, 412-416.
https://doi.org/10.1016/j.optmat.2018.12.008
[22] Jin, L., Zhang, L., Yang, L., Wu, X., Zhang, C., Wei, K., He, L., Han, X., Qiao, H., Asiri, A.M., Alamry, K.A. and Zhang, K. (2020) Orange-Red, Green, and Blue Fluorescence Carbon Dots for White Light Emitting Diodes. Journal of Materials Science & Technology, 50, 184-191.
https://doi.org/10.1016/j.jmst.2020.03.020
[23] Dang, H., Huang, L.K., Zhang, Y., Wang, C.F. and Chen, S. (2016) Large-Scale Ultrasonic Fabrication of White Fluorescent Carbon Dots. Industrial & Engineering Chemistry Research, 55, 5335-5341.
https://doi.org/10.1021/acs.iecr.6b00894
[24] Li, W., Guo, H., Li, G., Chi, Z., Chen, H., Wang, L., Liu, Y., Chen, K., Le, M., Han, Y., Yin, L., Vajtai, R., Ajayan, P. M., Weng, Y. and Wu, M. (2020) White Luminescent Single-Crystalline Chlorinated Graphene Quantum Dots. Nanoscale Horizons, 5, 928-933.
https://doi.org/10.1039/d0nh00053a
[25] Ding, H., Zhou, X.X., Zhang, Z.H., Zhao, Y.P., Wei, J.S. and Xiong, H.M. (2022) Large Scale Synthesis of Full-Color Emissive Carbon Dots from a Single Carbon Source by a Solvent-Free Method. Nano Research, 15, 3548-3555.
https://doi.org/10.1007/s12274-021-3891-0
[26] Dong, P., Jiang, B.P., Liang, W.Q., Huang, Y., Shi, Z. and Shen, X.C. (2017) Synthesis of White-Light-Emitting Graphene Quantum Dots via a One-Step Reduction and Their Interfacial Characteristics-Dependent Luminescence Properties. Inorganic Chemistry Frontiers, 4, 712-718.
https://doi.org/10.1039/c6qi00587j
[27] Feng, X., Zhang, F., Wang, Y., Zhang, Y., Yang, Y. and Liu, X. (2016) Fluorescent Carbon Quantum Dots as Single Light Converter for White LEDs. Journal of Electronic Materials, 45, 2784-2788.
https://doi.org/10.1007/s11664-016-4407-7
[28] Liu, W., Ng, K. W., Lin, H., Lian, Z., Su, S. and Wang, S. (2022) One-Step Synthesized Single Component White Emitting Carbon Microspheres for Lighting. Journal of Luminescence, 242, Article ID: 118606.
https://doi.org/10.1016/j.jlumin.2021.118606
[29] He, W., Weng, W., Sun, X., Pan, Y., Chen, X., Liu, B. and Shen, J. (2020) Multifunctional Carbon Dots with Solid-Liquid State Orange Light Emission for Vitamin B12 Sensing, Cellular Imaging, and Red/White Light-Emitting Diodes. ACS Applied Nano Materials, 3, 7420-7427.
https://doi.org/10.1021/acsanm.0c01003
[30] Chen, D., Chen, X., Gao, H. and Zhong, J. (2018) Red C-Dots and C-Dot Films: Solvothermal Synthesis, Excitation-Independent Emission and Solid-State-Lighting. RSC Advances, 8, 29855-29861.
https://doi.org/10.1039/c8ra06235h
[31] Zheng, J.X., Liu, X.H., Yang, Y.Z., Liu, X.G. and Xu, B.G. (2018) Rapid and Green Synthesis of Fluorescent Carbon Dots from Starch for White Light-Emitting Diodes. New Carbon Materials, 33, 276-287.
https://doi.org/10.1016/S1872-5805(18)60339-7
[32] Li, C.X., Yu, C., Wang, C.F. and Chen, S. (2013) Facile Plasma-Induced Fabrication of Fluorescent Carbon Dots toward High-Performance White LEDs. Journal of Materials Science, 48, 6307-6311.
https://doi.org/10.1007/s10853-013-7430-6
[33] Cheng, S., Ye, T., Mao, H., Wu, Y., Jiang, W., Ban, C., Yin, Y., Liu, J., Xiu, F. and Huang, W. (2020) Electrostatically Assembled Carbon Dots/Boron Nitride Nanosheet Hybrid Nanostructures for Thermal Quenching-Resistant White Phosphors. Nanoscale, 12, 524-529.
https://doi.org/10.1039/c9nr07785e
[34] Deodanes, O., Molina, J.C., Violantes, C., Pleitez, D., Cuadra, J., Ponce, H. and Rudamas, C. (2020) White Light Emitting CDs Quantum Dot Devices Coated with Layers of Graphene Carbon Quantum Dots. MRS Advances, 5, 3337-3343.
https://doi.org/10.1557/adv.2020.436
[35] Fang, M., Carneiro Neto, A.N., Fu, L., Ferreira, R.A.S., Bermudez, V.d.Z. and Carlos, L.D. (2022) A Hybrid Materials Approach for Fabricating Efficient WLEDs Based on Di-Ureasils Doped with Carbon Dots and a Europium Complex. Advanced Materials Technologies, 7, Article ID: 2100727.
https://doi.org/10.1002/admt.202100727
[36] Gao, Z., Sun, C., Liu, H., Shi, S., Geng, C., Wang, L., Su, S., Tian, K., Zhang, Z.H. and Bi, W. (2019) White Light-Emitting Diodes Based on Carbon Dots and Mn-Doped CsPbMnCl3 Nanocrystals. Nanotechnology, 30, 245201.
https://doi.org/10.1088/1361-6528/ab0b01
[37] Han, S., Chen, X., Hu, Y. and Han, L. (2021) Solid-State N, P-Doped Carbon Dots Conquer Aggregation-Caused Fluorescence Quenching and Couple with Europium Metal-Organic Frameworks toward White Light-Emitting Diodes. Dyes and Pigments, 187, Article ID: 109090.
https://doi.org/10.1016/j.dyepig.2020.109090
[38] He, J., Hong, Z., Yu, L., Hu, G. and Liu, X. (2021) Preparation of Controllable Luminescence CDs@MOFs Fluorescent Composites and Their Application in High Color Rendering White LED. Chinese Journal of Luminescence, 42, 984-996.
https://doi.org/10.37188/CJL.20210122.
[39] Huang, Y., Lin, H., Qiu, J., Luo, Z., Yao, Z., Liu, L., Liu, H., Tang, X. and Fu, X. (2020) High Color Rendering Indices of White Light-Emitting Diodes Based on Environmentally Friendly Carbon and Aizs Nanoparticles. Journal of Materials Chemistry C, 8, 7734-7740.
https://doi.org/10.1039/d0tc01192d
[40] Li, W., Wu, M., Jiang, H., Yang, L., Liu, C. and Gong, X. (2022) Carbon Dots/ZnO Quantum Dots Composite-Based White Phosphors for White Light-Emitting Diodes. Chemical Communications, 58, 1910-1913.
https://doi.org/10.1039/d1cc06180a
[41] Liang, J., Yang, B., Zhong, C.Y., Zhang, J., He, J., Chen, Y. and Liu, Z.Q. (2020) A Rapid in Situ Synthesis of Wide-Spectrum CD@BaCl2 Phosphors via Anti-Solvent Recrystallization for White LEDs. Inorganic Chemistry Frontiers, 7, 4845-4853.
https://doi.org/10.1039/d0qi01054e
[42] Lin, H., Yang, J., Liu, Y.F., Zeng, F.J., Tang, X.S., Yao, Z.Q., Guan, H.L., Xiong, Q., Zhou, J.E., Wu, D.F. and Du, J. (2020) Stable and Efficient Hybrid Ag-in-S/ZnS@SiO2-Carbon Quantum Dots Nanocomposites for White Light- Emitting Diodes. Chemical Engineering Journal, 393, Article ID: 124654.
https://doi.org/10.1016/j.cej.2020.124654
[43] Liu, K.K., Li, X.M., Cheng, S.B., Zhou, R., Liang, Y.C., Dong, L., Shan, C.X., Zeng, H.B. and Shen, D.Z. (2018) Carbon-ZnO Alternating Quantum Dot Chains: Electrostatic Adsorption Assembly and White Light-Emitting Device Application. Nanoscale, 10, 7155-7162.
https://doi.org/10.1039/c8nr01209a
[44] Lu, Y., Wang, S., Yu, K., Yu, J., Zhao, D. and Li, C. (2021) Encapsulating Carbon Quantum Dot and Organic Dye in Multi-Shell Nanostructured MOFo2s for Use in White Light-Emitting Diode. Microporous and Mesoporous Materials, 319, Article ID: 111062.
https://doi.org/10.1016/j.micromeso.2021.111062
[45] Sun, C., Zhang, Y., Sun, K., Reckmeier, C., Zhang, T., Zhang, X., Zhao, J., Wu, C., Yu, W.W. and Rogach, A.L. (2015) Combination of Carbon Dot and Polymer Dot Phosphors for White Light-Emitting Diodes. Nanoscale, 7, 12045-12050.
https://doi.org/10.1039/c5nr03014e
[46] Sun, C., Zhang, Y., Wang, Y., Liu, W., Kalytchuk, S., Kershaw, S.V., Zhang, T., Zhang, X., Zhao, J., Yu, W.W. and Rogach, A.L. (2014) High Color Rendering Index White Light Emitting Diodes Fabricated from a Combination of Carbon Dots and Zinc Copper Indium Sulfide Quantum Dots. Applied Physics Letters, 104, 261106.
https://doi.org/10.1063/1.4886415
[47] Wang, A., Hou, Y.L., Kang, F., Lyu, F., Xiong, Y., Chen, W.C., Lee, C.S., Xu, Z., Rogach, A.L., Lu, J. and Li, Y.Y. (2019) Rare Earth-Free Composites of Carbon Dots/Metal-Organic Frameworks as White Light Emitting Phosphors. Journal of Materials Chemistry C, 7, 2207-2211.
https://doi.org/10.1039/c8tc04171g
[48] Wang, Z., Hasnain, A., Sun, X., Han, Y., Liu, D., Tan, X., Ren, X.K. and Feng, Y. (2020) One-Pot Synthesis of Carbon Dots@ZrO2 Nanoparticles with Tunable Solid-State Fluorescence. Polymers for Advanced Technologies, 31, 1744-1751.
https://doi.org/10.1002/pat.4901
[49] Zhang, X., Sun, Z., Zhu, Z., Luo, J., Wu, Z. and Wang, Z. (2020) High-Efficient, Spherical and Thermal-Stable Carbon Dots@Silica Fluorescent Composite as Rare Earth-Free Phosphors for White LED. Ceramics International, 46, 14706- 14712.
https://doi.org/10.1016/j.ceramint.2020.02.274
[50] Zhang, Y., Zhang, J., Zhang, J., Lin, S., Huang, Y., Yuan, R., Liang, X. and Xiang, W. (2017) Intense Enhancement of Yellow Luminescent Carbon Dots Coupled with Gold Nanoparticles toward White LED. Dyes and Pigments, 140, 122-130.
https://doi.org/10.1016/j.dyepig.2017.01.043
[51] Chen, J., Liu, W., Mao, L.H., Yin, Y.J., Wang, C.F. and Chen, S. (2014) Synthesis of Silica-Based Carbon Dot/Nanocrystal Hybrids toward White LEDs. Journal of Materials Science, 49, 7391-7398.
https://doi.org/10.1007/s10853-014-8413-y