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Recently, Covalent Organic Frameworks (COFs) have emerged as an interesting class of porous materials, featuring tunable porosity and fluorescence properties based on reticular construction principles. Some COFs display highly emissive mono-colored luminescence, but, attaining white-light emission from COFs is difficult as it must account for a wide wave-length range. White-light emission is highly desired for solid state lighting applications and obtaining it usually demands the combination of red, green and blue light components. Hence, to achieve the targeted white-light emission, we report for the first time, grafting of lanthanides (Eu3+/Tb3+) on a 2D imine COF (TTA-DFP-COF). We studied the luminescence properties of the hybrid materials prepared by anchoring Eu3+ (red light) and Tb3+ (green light) β-diketonate complexes onto the TTA-DFP-COF. Reticular construction is exploited to design strong coordination of Eu3+ and Tb3+ ions into nitrogen rich pockets of the imine COF. Mixed Eu3+/Tb3+ materials are then prepared to incorporate red and green components along with the inherent blue light from the organic moieties of the COF to produce white-light emission. We show that COFs have the potential for hosting Eu3+ and Tb3+ complexes, which can be tuned to obtain desired excitations for applications in the field of optoelectronics, microscopy, optical sensing and bioassay.
This article was published in the following journal.
Name: ACS applied materials & interfaces
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Emission of LIGHT by a substance as its temperature is raised. It is sometimes called hot light in contrast to LUMINESCENCE.
Emission of LIGHT when ELECTRONS return to the electronic ground state from an excited state and lose the energy as PHOTONS. It is sometimes called cool light in contrast to INCANDESCENCE. LUMINESCENT MEASUREMENTS take advantage of this type of light emitted from LUMINESCENT AGENTS.
The use of green light-producing LASERS to stop bleeding. The green light is selectively absorbed by HEMOGLOBIN, thus triggering BLOOD COAGULATION.
Tunable liquid lasers with organic compounds (i.e., dye) which have a strong absorption band, used as the active medium. During emission, the dye has to be optically excited by another light source (e.g., another laser or flash lamp). The range of the emission wavelength may be anywhere from the ultraviolet to the near infrared (i.e., from 180 to 1100nm). These lasers are operated in continuous wave and pulsed modes. (UMDNS, 2005)
Lasers with a semiconductor diode as the active medium. Diode lasers transform electric energy to light using the same principle as a light-emitting diode (LED), but with internal reflection capability, thus forming a resonator where a stimulated light can reflect back and forth, allowing only a certain wavelength to be emitted. The emission of a given device is determined by the active compound used (e.g., gallium arsenide crystals doped with aluminum or indium). Typical wavelengths are 810, 1,060 and 1,300 nm. (From UMDNS, 2005)