Abstract
Based on blue LED chips to excite Ce-doped yttrium aluminum garnet (YAG: Ce3+) yellow phosphors, InP/ZnS green-emitting quantum dots (QDs) and InP/ZnSe/ZnS red-emitting QDs are used as light conversion materials for WLEDs to improve the color rendering index (CRI) of the device and improve its color coordinates. We have proven this in previous work. But in the previous work, we only studied the CRI of the driving current from 5 mA to 100 mA. The CRI and the Commission International de L’Eclairage (CIE) chromaticity coordinates of the WLED device prepared before is not ideal under high current conditions. The emission peak position of InP/ZnSe/ZnS red-emitting QDs we used in previous work is 605nm. In this article, we adjusted the emission peak position of InP/ZnSe/ZnS red-emitting QDs to 611nm, and prepared WLED in the same way, which improved the problem that the CRI of WLED devices decreases rapidly and the chromaticity coordinates change greatly under high current conditions. The CRI of prepared WLED device in this article was increased to 91.0, the CIE chromaticity coordinates is (0.3365, 0.3334), and the correlated color temperature (CCT) is 5313 K. We also tested the dependence of the electroluminescence (EL) spectrum, CRI, CCT and chromaticity coordinates of the prepared WLED device on the current. Compared with the prepared WLED device before, the CRI of the WLED device prepared in this article has always remained above 90, hovering between 90 ~ 91, very stable. The chromaticity coordinate distribution is also very concentrated, the amplitude of the offset black body radiation is small, and it shows excellent color rendering and stable working performance. A 30-day aging test was performed on the prepared WLED device.
Highlights
Light emitting diode (LED) is a solid-state semiconductor device that is widely used in many areas of daily life such as life lighting, traffic directions, display backlights, and so on [1]
On the basis of white LEDs (WLED) made of light conversion material, by adjusting the emission peak position of InP/ZnSe/ZnS red-emitting quantum dots (QDs), a WLED device was prepared in the same way, which improved its color rendering index (CRI) decreases rapidly under high current conditions, and the problem of large color coordinate changes, at the same time, the CRI of the prepared WLED device was increased to 91.0, the Commission International de L’Eclairage (CIE) chromaticity coordinate was (0.3365, 0.3334), and the correlated color temperature (CCT) was 5313 K
By comparing the best electroluminescence performance of the WLED I device and the WLED II device, it can be seen that after the InP/ZnSe/ZnS red-emitting QDs emission peak is red-shifted by 5 nm, the maximum CRI of the WLED device increases by 0.7, the light effect is increased by 20.43 lm/w, and maintains a good color coordinate close to standard white light
Summary
Light emitting diode (LED) is a solid-state semiconductor device that is widely used in many areas of daily life such as life lighting, traffic directions, display backlights, and so on [1]. In this article, based on the previously mentioned blue LED chip excited YAG: Ce3+ yellow phosphor, superimposed InP/ZnS green-emitting quantum dots (QDs) and InP/ZnSe/ZnS red-emitting QDs. On the basis of WLED made of light conversion material, by adjusting the emission peak position of InP/ZnSe/ZnS red-emitting QDs, a WLED device was prepared in the same way, which improved its CRI decreases rapidly under high current conditions, and the problem of large color coordinate changes, at the same time, the CRI of the prepared WLED device was increased to 91.0, the CIE chromaticity coordinate was (0.3365, 0.3334), and the CCT was 5313 K.
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