Abstract
Colloidal quantum dots which can emit red, green, and blue colors are incorporated with a micro-LED array to demonstrate a feasible choice for future display technology. The pitch of the micro-LED array is 40 μm, which is sufficient for high-resolution screen applications. The method that was used to spray the quantum dots in such tight space is called Aerosol Jet technology which uses atomizer and gas flow control to obtain uniform and controlled narrow spots. The ultra-violet LEDs are used in the array to excite the red, green and blue quantum dots on the top surface. To increase the utilization of the UV photons, a layer of distributed Bragg reflector was laid down on the device to reflect most of the leaked UV photons back to the quantum dot layers. With this mechanism, the enhanced luminous flux is 194% (blue), 173% (green) and 183% (red) more than that of the samples without the reflector. The luminous efficacy of radiation (LER) was measured under various currents and a value of 165 lm/Watt was recorded.
Highlights
In the past decade, the gallium nitride-based light-emitting diodes (LEDs) have been widely used as a solid-state lighting source or the backlight unit (BLU) of liquid crystal display (LCD) owing to their high luminous efficiency, low cost, long lifetime and environmental sustainability [1,2,3,4,5,6]
The light utilization efficiency (LUE) of the LCD display system is still lower than 2.8% [9], and this means the display needs to be operated at more than ten times of brightness in order to meet the expected output optical power
We report a BLU-free full-color LED based display by combining UV micro LED arrays with RGB QDs via aerosol jet printing
Summary
The gallium nitride-based light-emitting diodes (LEDs) have been widely used as a solid-state lighting source or the backlight unit (BLU) of liquid crystal display (LCD) owing to their high luminous efficiency, low cost, long lifetime and environmental sustainability [1,2,3,4,5,6]. These devices usually suffered from the weak luminous efficiency (below 20 lm/w), limited choices for carrier transport matching layers, and shorter-than-expect emission lifetime To relieve from these limitation, we believe using CQD layer as a passive photon conversion mechanism should suffice for high quality and multiple color generation. In order to spraying the QDs uniformly, different methods have been used to deposit the QDs for display technology and light emitting applications, including spin coating, mist coating, pulse-spray coating, stamp printing, and inkjet printing [25,31,32,33,34,35,36] Among these manufacturing technologies, spin coating, mist coating, and pulse-spray coating are for the low-resolution patterns and bear high material loss [25,35]. Combining the micro LED arrays and RGB QDs with highly reflective DBR exhibits a full-colored display technology and provides an alternative method for display applications
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