Craig Breen

A Wafer‐Level Integrated White‐Light‐Emitting Diode Incorporating Colloidal Quantum Dots as a Nanocomposite Luminescent Material

High-brightness, color-tunable colloidal quantum dots are incorporated in 3D nanoporous GaN to create a nanocomposite material (CQD/NP-GaN), which is demonstrated to be an effective approach for a wavelength down-conversion nanomaterial in solid-state lighting. The white-light-emitting diode (LED) made from a blue GaN-based LED and the CQD/NP-GaN shows an increase of extraction efficiency by a factor of 2, a controllable white color, and a down-conversion quantum efficiency as high as 82%.

Highly efficient, spatially coherent distributed feedback lasers from dense colloidal quantum dot films

Colloidal quantum dots (CQD) are now making their entry to full-color displays, endowed by their brightness and single-material base. By contrast, many obstacles have been encountered in their use towards lasers. We demonstrate here optically pumped distributed feedback (DFB) lasers, based on close-packed, solid films self-assembled from type-I CQDs. Notably, the single mode CQD-DFB lasers could reach such a low threshold as to be pumpable with a compact pulsed source in a quasi-continuous wave regime. Our results show the spatially and temporally coherent laser beam outputs with power of 400 μW and a quantum efficiency of 32%.

12.2: Invited Paper: Quantum Dot Light Emitting Diodes for Near-to-eye and Direct View Display Applications

Quantum dot light emitting diodes QLEDs are a printable thin film electroluminescent technology that can deliver exceptional color and efficiency at low cost of manufacture for display and solid-state lighting applications. However, while most literature reports focus on the performance of individual test pixels, examples of working display prototypes have been sorely lacking. We report on our progress developing QLEDs for near-to-eye and direct view display applications. Both a 4″ diagonal active-matrix bottom-emitting monochrome QLED display and an 800×600 SVGA top-emitting monochrome QLED microdisplay are reported on and their performance summarized. Contract printing of high-resolution RGB QDs is also demonstrated as a milestone towards full-color displays.

P-176: Progress in Developing High Efficiency Quantum Dot Displays

LED displays utilizing quantum dots (QDs) as emitters offer several key advantages over traditional OLEDs, combining the solution processability of polymers with the high efficiency potential of phosphors, all with the stability benefits of an inorganic emitter. While QD-LEDs are at an early stage in their development, the effort toward commercialization has already led to the identification of several considerations particular to QD-LEDs. This paper explores material and design considerations for QD-LEDs and reports our progress in developing QD-LEDs for information display and advanced applications.

32.4: Quantum Dot Light Emitting Diodes for Full‐color Active‐matrix Displays

Quantum dot light emitting diodes (QLEDs) are a printable thin film electroluminescent technology that delivers exceptional color and efficiency at low cost of manufacture for display and solid- state lighting applications. We report on our progress developing efficient, stable QLEDs for full-color active-matrix displays, including recent advances in device performance, lifetime and Cadmium-free QLEDs. Current QLED devices exhibit peak luminance efficiencies exceeding 50 cd/A, luminous power efficiencies greater than 20 lm/W and operational lifetimes exceeding 300 hours at 1,000 nits. Our most recent QLED efficiency results suggest that todays QLED performance is within a factor of two of the theoretical limit.

Transient gain spectroscopy in the potent single-exciton regime of dense II-VI colloidal quantum dot films

We have reached the long-sought single exciton gain regime in dense colloidal II-VI semiconductor quantum dot films. Transient spectroscopy details their exciton dynamics, informing further development of single material based lasers across the visible.

Wavelength engineered luminescent material incorporating colloidal quantum dot within a nanoporous gallium nitride matrix

A new nanocomposite material was created by embedding colloidal CdSe-based quantum dots (QDs) within single crystal nanoporous gallium nitride (GaN) host. High efficiency luminescence and wavelength-engineered ability of colloidal QDs combined with high performance of nitride blue LEDs suggest this nanomaterials potential for solid state lighting.

Red, green, and blue laser action in solid colloidal quantum dot films

We report on wavelength-variable lasing from optical gain media composed of colloidal quantum-dots (CQD) thin films across the visible spectrum. Exploiting single exciton gain enables amplified spontaneous emission (ASE) and vertical cavity lasing at very low optical pump thresholds. The average number of exciton per CQD at the ASE threshold is <;N>;~ 0.8, which significantly reduces losses from enhanced nonradiative multiexciton Auger recombination in nanometer sized semiconductor particle, enabling quasi-continuous-wave CQD laser performance in densely packed nanocomposites.

Optical gain and green/red vertical cavity surface emitting lasing from cdse-based colloidal nanocrystal quantum dot thin films

We demonstrate robust excitonic gain from colloidal close-packed, CdSe-based nanocrystal quantum dot thin films at record low threshold excitation energy of 90 μJ/cm2 for amplified spontaneous emission. The optical gain is employed in pulsed optically pumped quantum dot vertical cavity surface emitting lasers in the green and the red, respectively.