**4. Conclusions**

*Quantum Dots - Fundamental and Applications*

**76**

**Figure 8.**

full width at half maximum (FWHM) value is 44 nm through the spectrum. The peak wavelength of QLED electroluminance spectra is 2 nm red shift compared with the peak wavelength of QD solution, which might be because of the dot-to-dot interactions in the close-packed solid film. Moreover, the electric field induced the Stark effect [20]. The 1931 CIE coordinate after emission is (0.31, 0.66) as shown in **Figure 8(c)**.

*(a) The QLED current density versus the voltage (J-V) curve, (b) the QLED electroluminance spectra as the* 

*applied voltage increased and (c) the 1931 CIE coordinate of QLED.*

This work discussed the structure and mechanism of QLED and demonstrated an all-solution process of QLED in the last section. The QLED has high luminance with low turn-on voltage. These properties, caused by the use of ZnO NPs, improve electron injection and enhance radiative recombination. The resulting QLED fabrication process also makes printing QLED a possible method in the future.
