NanoPhotonica (United States)

Solution processed electroluminescent displays made with quantum dot emitter is the next‐generation display technology because of high efficiency, wide‐color gamut, low turn‐on voltage, thin form factor, and low manufacturing cost. We have shown highly efficient quantum dot light emitting diode (QLEDs) using colloidal quantum dot as an emitter and zinc oxide nanocrystal as an electron transport layer. Here, we will present red and green QLEDs with external quantum efficiency (EQE) ≥ 20% and blue QLEDs with EQE > 15%. We will also show the performance improvements of QLEDs using short‐time annealing process and using doped zinc oxide nanocrystal.

Molecular self-assembly of block copolymers has been pursued as a next generation high-resolution, low-cost lithography technique. Solvent vapor annealing is a promising way of achieving self-assembled patterns from polymers with high interaction parameters, χ, or high molecular weights. Compared to thermal annealing, the assembly in a solvated state can be much faster, but the film swelling process is typically challenging to control and reproduce. We report the design and implementation of an automated solvent annealing system that addresses these issues. In this system the film swelling is controlled via local heating or cooling, which enables exceptionally fast and precise modulation of the swelling. The swelling of the polymer films follows preprogrammed annealing profiles with the help of a feedback loop that compares and tunes the film thickness with respect to the set point. The system therefore enables complex annealing profiles such as rapid cyclic swelling and deswelling. We show that the orientation of the pattern morphology and the amount of lattice defects are influenced by the used annealing profile. We demonstrate that optimized profiles significantly shorten the annealing time (<15 min) of high-χ and high-molecular weight poly(styrene-b-2-vinylpyridine).

Displays made using colloidal quantum dots as electroluminescent (EL) emitter is a very promising display technology because it is efficient, emits pure color, and is inexpensive. We have demonstrated highly efficient red, green, and blue quantum dot light emitting diodes (QLEDs) using a colloidal zinc oxide nanoparticle electron transport layer. Here, we will report QLEDs with external quantum efficiency &gt;15% for red, green, and blue color (approaching the theoretical‐limit of ~22% for green) QLEDs. Finally, we will discuss some of the challenges that must be addressed to successfully commercialize EL‐QLED displays.

Abstract Colloidal quantum‐dot based hybrid light‐emitting diodes (QD‐LEDs) that exhibit high efficiency, long lifetime, solution processability, color tunability and narrow emission bandwidth are reported. The devices possess maximum current and power efficiency of 3.2 cd/A and 2.1 lm/W for blue, 60 cd/A and 54 lm/W for green, and 15 cd/A and 18 lm/W for red emission. With exceptional good lifetime, the current QD‐LEDs are promising for flat panel display applications.