【摘要】：發(fā)光二極管（LED）具有能耗低、光效高以及壽命長等優(yōu)點(diǎn)，近年來受到科學(xué)界和產(chǎn)業(yè)界的廣泛關(guān)注。實(shí)際應(yīng)用中，以單一基質(zhì)白光熒光粉的研究最為關(guān)鍵。白光LED用熒光粉分為稀土基熒光粉、膠體量子點(diǎn)熒光粉以及碳點(diǎn)（Carbon dots，CDs）熒光粉三大類。其中，CDs由于具有熒光量子產(chǎn)率高、穩(wěn)定性高及毒性低等優(yōu)點(diǎn)，成為近年來發(fā)光材料研究的熱點(diǎn)。 為了提高白光LED用CDs熒光粉的熒光量子產(chǎn)率和藍(lán)、綠、紅光總比重，本論文以一水合檸檬酸為碳源，分別以乙二胺、硫脲和L-半胱氨酸為添加劑，在不同溫度下水熱反應(yīng)6h，制得氮摻雜碳點(diǎn)（Nitrogen-doped CDs,N-CDs）與氮硫摻雜碳點(diǎn)（Nitrogen and sulphur-doped CDs, NS-CDs），并對其進(jìn)行結(jié)構(gòu)和光學(xué)性質(zhì)分析。優(yōu)選熒光量子產(chǎn)率最高且藍(lán)、綠、紅光總比重較高的產(chǎn)物N-CDs4和NS-CDs9，并以其為熒光粉制作了白光LED，對白光LED的色坐標(biāo)和相關(guān)色溫（Correlated color temperature, CCT）進(jìn)行了表征。 通過研究，得到以下結(jié)論： (1) N-CDs的制備與性質(zhì)。隨著乙二胺添加量的增加，N-CDs的熒光量子產(chǎn)率先增高、后降低。在160-200℃內(nèi)，其熒光量子產(chǎn)率基本不隨反應(yīng)溫度的變化而變化。乙二胺添加量和反應(yīng)溫度基本不影響N-CDs的光譜組成。當(dāng)一水合檸檬酸與乙二胺摩爾比為1:4，反應(yīng)溫度為200℃時，得到最優(yōu)N-CDs4，其熒光量子產(chǎn)率為67.06%；在光譜中，，紅、綠、藍(lán)光總比重為53.01%，均高于目前文獻(xiàn)所報道的最高值。具有兩個熒光中心，壽命為17.0ns的熒光中心向壽命為11.1ns的熒光中心發(fā)生了能量轉(zhuǎn)移。C-N基團(tuán)的引入能夠提高N-CDs的熒光量子產(chǎn)率。 (2) NS-CDs的制備與性質(zhì)。隨著硫脲添加量的增加，含C=S官能團(tuán)NS-CDs的熒光量子產(chǎn)率先增高、后降低；在160-200℃內(nèi)，該NS-CDs的熒光量子產(chǎn)率隨反應(yīng)溫度的升高而增加；藍(lán)、綠、紅光總比重隨硫脲添加量和反應(yīng)溫度的增加而降低。當(dāng)一水合檸檬酸與硫脲摩爾比為1:1，反應(yīng)溫度為200℃時，得到最優(yōu)NS-CDs3。其熒光量子產(chǎn)率為9.80%；在光譜中，紅、綠、藍(lán)光總比重為47.82%；平均熒光壽命為8.88ns；其熒光衰減曲線符合三指數(shù)函數(shù)，意味著NS-CDs3有三個熒光中心。 而含有C-S官能團(tuán)的NS-CDs9的熒光量子產(chǎn)率高達(dá)65.37%，紅、綠、藍(lán)光總比重高達(dá)61.93%。較C-S官能團(tuán)，C=S官能團(tuán)不利于CDs熒光量子產(chǎn)率的提高。S元素的引入能夠有效提高NS-CDs的藍(lán)、綠、紅光總比重。 (3)白光LED的制備與光學(xué)性能。采用具有最高熒光量子產(chǎn)率和較高藍(lán)、綠、紅光總比重的N-CDs4和NS-CDs9作為熒光粉制備了白光LED。N-CDs4基白光LED色坐標(biāo)為（0.38，0.42），CCT為4290K。NS-CDs9基白光LED色坐標(biāo)為（0.32,0.36），CCT為5822K。光學(xué)密封膠和聚乙烯醇水凝膠使CDs發(fā)射光譜產(chǎn)生明顯紅移，全部覆蓋可見光區(qū)。實(shí)現(xiàn)LED直接發(fā)射白光。
[Abstract]:Light emitting diode (LED) has attracted much attention in recent years because of its advantages of low energy consumption, high light efficiency and long lifetime. In practical application, the study of single substrate white phosphor is the most important. White LED phosphors are divided into three categories: rare earth based phosphors colloidal quantum dots phosphors and carbon dots (Carbon dots,CDs) phosphors. Due to their advantages of high fluorescence quantum yield, high stability and low toxicity, CDs have become a hot spot in the research of luminescent materials in recent years. In order to improve the fluorescence quantum yield and the specific gravity of blue, green and red light of CDs phosphors for white LED, in this paper, citric acid monohydrate was used as carbon source, ethylenediamine, thiourea and L-cysteine were used as additives, respectively. Nitrogen doped carbon point (Nitrogen-doped CDs,N-CDs) and nitrogen sulfur doped carbon point (Nitrogen and sulphur-doped CDs, NS-CDs) were prepared by hydrothermal reaction at different temperatures for 6 h, and their structures and optical properties were analyzed. N-CDs4 and NS-CDs9, which have the highest fluorescence quantum yield and blue, green and high specific gravity of red light, were selected, and the white LED, was used as phosphors to characterize the color coordinates and related color temperature (Correlated color temperature, CCT) of white LED. The main conclusions are as follows: (1) preparation and properties of N-CDs. With the addition of ethylenediamine, the fluorescence quantum production of N-CDs firstly increased and then decreased. In the temperature range of 160 鈩

本文編號：2204696