Freestanding High-Resolution Quantum Dot Color Converters with Small Pixel Sizes

Designing the next generation of high-resolution displays requires high pixel density per area and small pixel sizes without compromising the optical quality. Quantum dots (QDs) have been demonstrated as a promising material system for down-conversion of blue emission as they provide pure colors on the wide color gamut. However, for high color-conversion efficiency, the required QD film thickness has not been compatible with small pixel sizes. In this work, we develop a new type of freestanding QD-based color converter for efficient optical down-conversion from inorganic blue light-emitting diodes (LEDs) in a color-by-blue configuration. CdSe/ZnS core-shell QDs in a UV-curable polymer matrix are encapsulated within cavities formed by patterning and bonding a pair of patterned quartz substrates. By controlling the required QD thickness and the pixel size independently, we demonstrate freestanding monochrome red and green converters with small pixel sizes down to 5 × 5 μm² and a high resolution of >3600 ppi. The optical studies show that the QD film thickness required for efficient color conversion can be successfully realized even for the small pixel sizes. We further combine green and red pixels in a single converter to achieve white emission when combined with blue LED emission. The QD color converter design and processing are decoupled from the LED fabrication and can be easily scaled to wafer-size integration with arbitrary pixel sizes for QD-based RGB displays with ultrahigh resolution.

Sunlike White-Light-Emitting Diodes Based on Zero-Dimensional Organic Metal Halide Hybrids

Here we report ultraviolet (UV)-pumped white-light-emitting diodes (WLEDs) with sunlike full spectrum emissions, by using a commercially available blue phosphor (BaMgAl₁₀O₁₇:Eu²⁺) and a series of broadband zero-dimensional (0D) organic metal halide hybrids as down conversion phosphors. By controlling the blend ratio of phosphors, we have achieved high-quality WLEDs with excellent general color rendering index (CRI R_a) of up to 99 and deep-red rendering index (R9) of up to 99. These WLEDs exhibiting white emissions with correlated color temperatures (CCTs) ranging from 3000 to 6000 K perfectly mimic sunlight at different times of day.

Synthesis and luminescence characteristics of fine-sized Ba3Si6O12N2:Eu green phosphor through spray pyrolysis using TEOS/Si3N4 mixed precursors

A fine-sized Ba₃Si₆O₁₂N₂:Eu³⁺ green phosphor with good luminescence and thermal quenching properties was prepared by spray pyrolysis using a mixture of TEOS and Si₃N₄ nanoparticles as the Si precursor.