Structural Properties of QLED Based on Hybrid Quantum Dots

In order to study the structure and properties of QLED based on hybrid quantum dots, QLED devices were prepared using red light quantum dots and green light quantum dots as the light-emitting layer, and their properties were characterized. The structure of the device fabricated was ITO/PEDOT:PSS/poly-TPD/hybrid QDs/ZnO/Al, in which three kinds of hybrid quantum dot light-emitting layer were adopted. The red light quantum dot layer was spin coated firstly in the solution 1, followed with spin-coating green light quantum dot layer. The solution 2 first spin-coated green light quantum point layer, red quantum dot layer was spin-coated after that. In the solution 3, red and green quantum dots were mixed with the proportion of 1:1 and was then spin-coated as the light-emitting layer. The experimental results show that the device prepared by the solution 1 has the largest current density, lowest luminous intensity and only exhibit red light. The device prepared by the solution 2 has the minimum current density, and has the spectra of both red and green light. The maximum current efficiency is 4.69 cd/A at the external bias of 8 V. The device prepared by the solution 3 also exhibits red and green light, the current density and the luminous intensity are lower than that of the device prepared by the solution 2. It can be concluded from the energy level that the device prepared by the solution 2 has a double energy trap, therefore, it is advantageous in trapping both holes and electrons to the red light quantum dot layer. It is achievable to further improve the device efficiency by adjusting the thickness of each functional layer to balance the carrier injection.