基于煤沥青的绿光碳点制备及其在白光LED中的应用

Green fluorescent carbon dots preparation and white light emitting diodes application research based on coal pitch

为了实现煤沥青的高值利用,以煤沥青为碳源,邻/间/对苯二胺分别为氮源,通过先化学氧化、后水热两步法制备了三种高量子产率(QY)的氮掺杂碳点,分别标记为:CP-OCDs、CP-MCDs和CP-PCDs,并做了空白对照实验。结果显示,CP-OCDs、CP-MCDs和CP-PCDs的紫外可见吸收、激发和发射光谱与空白样品均不相同,氮掺杂改变了未掺氮碳点(CP-CDs和CP-HCDs)的吸收和荧光性质,并提高了QY。当最佳激发波长分别为385、385和365 nm时,CP-OCDs、CP-MCDs和CP-PCDs的最大发射波长分别为525、515和500 nm,都发明亮的绿光,QY分别为29.21%,19.86%和14.14%,高于CP-CDs和CP-HCDs的QY(4.90%和6.97%)。QY最高的碳点为CP-OCDs。CP-OCDs为分散性好、粒径为2-5 nm的无定形碳纳米粒子,其表面和骨架内部含有大量氨基和酰胺基团,这些含氮官能团引起CP-OCDs的荧光明显增强。将CP-OCDs作为荧光粉,结合紫外芯片制备了3.2 V下发白光的LED,器件的发射光谱几乎跨越了整个可见光区,色坐标(0.30,0.34),显色指数81,色温7293 K,流明效率3.42 lm·W^(-1),发明亮的冷白光,并具有高的光和色稳定性,CP-OCDs在固态照明领域具有较大的应用潜力。

In order to realize the high value utilization of coal pitch,three kinds of nitrogen doped carbon dots with high fluorescence quantum yield(QY)were prepared via chemical oxidation followed by hydrothermal method using coal pitch as the carbon source and o-phenylenediamine,m-phenylenediamine and p-phenylenediamine as the nitrogen source respectively,which were labeled as CP-OCDs,CP-MCDs and CP-PCDs.Blank experiments were also done.Results showed that the UV-visible absorption,excitation and emission spectra of CP-OCDs,CP-MCDs and CP-PCDs were different from blank samples.Nitrogen doping changed the absorption and emission spectral properties of CP-CDs and CP-HCDs,along with increased QY.While the optimal emission wavelengths were 385,385 and 365 nm for CP-OCDs,CP-MCDs and CP-PCDs,the maximum emission wavelengths were 525,515 and 500 nm,respectively.All of them emit bright green light.The QY were 29.21%,19.86%and 14.14%,which were higher than that of CPCDs and CP-HCDs(4.90%and 6.97%).The optimal carbon dots were CP-OCDs.CP-OCDs were amorphous carbon nanoparticles with good dispersion and particle size of 2-5 nm,along with a large number of amino and amide groups exist on their surface and inside the skeleton.These nitrogen-containing functional groups cause significantly enhanced fluorescence of CP-OCDs.A white LED was fabricated by combining CP-OCDs phosphors with a ultraviolet chip,whose emission spectrum spaned almost the entire visible range,which emitted cool white light with a CIE coordinate of(0.30,0.34),a color rendering index of 81,a correlated color temperature of 7293 K and luminous efficiency of 3.42 lm·W^(-1).In addition,the white LED under 3.2 V exhibited good optical and color stability.This research suggested the great potential of CP-OCDs for solid-state lighting field.