To improve the photoluminescence quantum yield (PL QY) and the environmental stability of the CsPbCl 3 quantum dots (QDs), the Mn doping strategy has been applied first. The substitute of Mn 2 + can reduce the toxicity of the lead element firstly, and then slightly enhance the stability of QDs. Increasing the nominal content of Mn, the longtime duration of the intrinsic excitation peak is significantly improved; and at a higher nominal content, a wide red emission by the d-d transition of Mn 2 + is introduced, the overall PL QY of CsPbCl 3 QDs increases to 54.32 %. Secondly, to further prevent the penetration of oxygen and water, the Mn-doped CsPbCl 3 @SiO 2 nano-composite with a physical coating shell was synthesized by the hydrolysis of aminopropyltriethoxysilane. The investigation on the PL spectrum within hours shows that the relative peak intensity maintains 74 % of the initial intensity and the shift of peak position is also inhibited. Finally, the nano-composite materials were fabricated into white light-emitting devices (WLED), under the illumination of a commercial GaN chip, the device shows a good Commission Internationale de lEclairage (CIE) color coordination of (0.31,0.35). As a result, the obtained Mn-doped CsPbCl 3 @SiO 2 QDs have excellent optical properties and good stability under aqueous and polar solvent environments. Therefore, this doping and coating method could pave the way for future applications in illumination and display fields.
The effects of elemental
tellurium doping and decorating on the
photoluminescence quantum yield (PL QY) and the environmental stability
of the CsPbBr
3
quantum dots (QDs) have been systematically
studied. The PL spectra blue-shifts from 520 to 464 nm gradually with
the increase in the amount of Te, and the full width at half-maximum
(FWHM) increases from 20 to 62 nm and decreases to 27 nm accordingly.
The morphology of the untreated samples has a rectangular shape with
distinct boundaries, whereas the Te-doped samples have a semi-core–shell
structure with partially coated CsPb
2
Br
5
after
tellurium doping. Furthermore, the apparent size of the nanocomposites
increases to 20 nm, but the crystal size of the core decreases slightly
according to the broadened peaks of X-ray diffraction (XRD). Further
investigation by X-ray photoelectron spectroscopy shows that the binding
energy of Pb–Br increases and Pb–Te bonds are formed
in Te-doped samples, which can enhance the stability of QDs from the
view of strengthening the chemical bonds and inhibiting the detaching
behavior of bromine under moisture. At the nominal content of Pb/Te
= 1:0.4, the thermal decomposition temperature of the QDs increases
from 300 to 500 °C; the maximum of PL QY increases to 70% for
the 1:0.4 sample and the relative PL peak intensity maintains 50%
of the initial value after a 60 h aging simulation. Finally, the nanocomposite
materials are fabricated into a white light-emitting device (WLED).
Under the illumination of a commercial GaN chip, the device shows
a good Commission Internationale de lEclairage (CIE) color coordination
of (0.3291,0.3318).
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