Solution-processed planar white light-emitting diodes based on cadmium-free Cu-In-Zn-S/ZnS quantum dots and polymer

- White light-emitting diodes were fabricated based on cadmium-free Cu-In-Zn-S-based QDs and polymer via a simple solution-processed technique.
- White electroluminescence was obtained under the annealing temperature of 95 °C.
- The WLEDs exhibited a high CRI of 90 with a CIE coordinate of (0.33, 0.32).

Bright white light-emitting diodes (WLEDs) were fabricated by using a simple solution-processed technique, in which the yellow cadmium-free Cu-In-Zn-S/ZnS core/shell quantum dots (QDs) blending with poly [(9, 9-dioctylfluorenyl-2, 7-diyl)-co-(4, 4′-(N-(p-butylphenyl)) diphenylamine)] (TFB) was used as emissive layers. The color of the electroluminescence (EL) from the device could be tuned from blue-green to white by varying the thermal annealing temperatures, and white EL emission could be obtained under the annealing temperature of 95 °C. A high color rendering index (CRI) of 90 and the Commission Internationale de l'Eclairage (CIE) color coordinates of (0.33, 0.32) were achieved in the WLEDs annealed at 95 °C, respectively. The WLEDs exhibited a low turn-on voltage of 2.5 V and a maximum luminance of 1500 cd/m2, which were maintained at 0.1 cd/A over a wide range of luminance from 100 to 1300 cd/m2. This work may open up a new way to realize white light in the planar WLEDs based on the cadmium-free QDs.

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