One-step synthesis of yellow-emitting carbogenic dots toward white light-emitting diodes

Carbon dots (CDs) were hydrothermally synthesized using citric acid as carbon source and ethylenediamine as additive. The as-obtained CDs were then subjected to ultraviolet (UV) irradiation, resulting in ultraviolet-irradiated CDs (UVCDs). The morphology and size of CDs were characterized by transmission electron microscopy. Elemental analysis (EA) was employed to explore the composition of CDs. The surface functional groups of CDs were investigated with the help of Fourier transformation infrared spectroscopy. Fluorescence spectrometry and ultraviolet-visible (UV-vis) spectrophotometry were used to characterize the optical properties of CDs and UVCDs. The results show that the size of CDs was around 10 nm. C, H, O and N constituted CDs with the empirical elemental composition CH 1.26 O 0.52 N 0.22 . Apart from excitation-independent photoluminescence (PL), CDs exhibited two UV-vis absorption peaks at 340 and 451 nm. They also revealed weak near infrared (NIF) emission with excitation at 340and 360 nm. In addition to excitation-dependent PL, UVCDs showed one UV-vis absorption peak at 340 nm and extension of UV-vis absorption band to visible range, and they also displayed weak NIF emission at 340 and 360 nm excitation. Optical behaviors originated from surface defects and band bending. The as-prepared CDs could be used to harvest solar energy.

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“…Some groups utilized PL feature of CDs. Chen group [30] demonstrated yellow-emitting CDs prepared by a one-step pyrolysis from N-acetylcysteine.…”

Section: Introductionmentioning

confidence: 99%

Carbon Dots: From Intense Absorption in Visible Range to Excitation-Independent and Excitation-Dependent Photoluminescence

Zhao

Liu

Yang

et al. 2015

Fullerenes, Nanotubes and Carbon Nanostructures

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“…[2,7,11,12] To date, the vast majority of the applications related to CQDs are in the field of medical diagnostics and bioimaging. [13][14][15] Recently, CQDs have also been used for catalysis, [7] and the development of novel optoelectronic materials, such as LEDs [16,17] and solar cells, where mesoporous TiO 2 was sensitized with CQDs derived from the dehydration of g-butyrolactone using sulfuric acid. [18] In addition, the related graphene quantum dots have been used as sensitizers in ZnO nanorod-based solar cells, but this carbon material was produced using top-down methods.…”

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confidence: 99%

Biomass‐Derived Carbon Quantum Dot Sensitizers for Solid‐State Nanostructured Solar Cells

et al. 2015

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New hybrid materials consisting of ZnO nanorods sensitized with three different biomass-derived carbon quantum dots (CQDs) were synthesized, characterized, and used for the first time to build solid-state nanostructured solar cells. The performance of the devices was dependent on the functional groups found on the CQDs. The highest efficiency was obtained using a layer-by-layer coating of two different types of CQDs.

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“…[12][13][14][15][16] Chen's group has suggested CDs as a phosphor for WLEDs; however, these luminophores can hardly generate warm white light with high CRI for indoor lighting because of their low emission efficiency in the yellow and red regions. This issue can be overcome by a combination of CDs with other phosphors, to enhance the color rendering index and tune the correlated color temperature (CCT).…”

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confidence: 99%

High color rendering index white light emitting diodes fabricated from a combination of carbon dots and zinc copper indium sulfide quantum dots

Sun

Zhang

Wang

et al. 2014

Applied Physics Letters

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In a line with most recent trends in developing non-toxic fluorescent nanomaterials, we combined blue emissive carbon dots with green and red emissive zinc copper indium sulfide (ZCIS) core/shell quantum dots (QDs) to achieve white light-emitting diodes (WLEDs) with a high color rendering index of 93. This indicates that ZCIS QDs, with their broad emission bands, can be employed to effectively make up the emission of carbon dots in the yellow and red regions to produce WLEDs in the wide region of color temperature by tuning the volume ratio of these constituting luminophores. Their electroluminescence characteristics including color rendering index, Commission Internationale de l'Eclairage (CIE) color coordinates, and color temperatures were evaluated as a function of forward current. The CIE-1931 chromaticity coordinates of the as-prepared WLEDs, exhibiting good stability, were slightly shifted from (0.321, 0.312) at 10 mA to (0.351, 0.322) at 30 mA, which was mainly caused by the different thermal quenching coefficients of carbon dots and ZCIS QDs.

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One-step synthesis of yellow-emitting carbogenic dots toward white light-emitting diodes

Cited by 92 publications

References 38 publications

Carbon Dots: From Intense Absorption in Visible Range to Excitation-Independent and Excitation-Dependent Photoluminescence

Carbon Dots: From Intense Absorption in Visible Range to Excitation-Independent and Excitation-Dependent Photoluminescence

Biomass‐Derived Carbon Quantum Dot Sensitizers for Solid‐State Nanostructured Solar Cells

High color rendering index white light emitting diodes fabricated from a combination of carbon dots and zinc copper indium sulfide quantum dots

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