QD-OLED device performance is unsatisfactory nowadays, due to the limited efficiency of blue OLED material as well as the low efficient converting rate of QD material. Here we proposed a novel structure of QD-OLED, using white OLED as the excitation. The device shows higher optical efficiency compared with QD-OLED with Blue OLED as excitation. In addition, a 6.6 inch green QD-OLED was demostrated with the proposed structure.

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Liquid-crystal display (LCD) with patterned quantum dot (QD) film and short-pass reflector (SPR) was proposed and has an advantage for dramatically enhancement of optical efficiency compared to LCD prepared with a mixed QD film (reference). In proposed LCD structure, the optical power in blue, green, and red color was increased by 869%, 256%, and 85% compared with the reference, respectively. This enhancement comes from the two facts; 1) blue backlight is converted to green or red light separately by each patterned green or red QD film entered directly to each CF without any different color cut, 2) SPR reflects the backward emission of QD to forward direction, preventing the absorption loss of backward emission by back light unit. Additionally, we obtained high color gamut of NTSC 125% in our proposed LCD using a broad-band CF while maintaining the maximum optical intensity with relatively high CF transmittance. Author KeywordsLiquid-crystal display (LCD); quantum dot (QD); nanocrystal; patterned QD film; short-pass reflector (SPR); optical efficiency.

Since the reabsorption loss among different size quantum dots (QDs) is a critical issue in the QD based white LEDs, we proposed and fabricated new film structure of 2D island-patterns consisting of separate green and red QDs dispersed photopolymer patterns in a zigzag form. A small air-gap such as 60 μm between QD islands helps to control the optical path at the interface to reduce the lateral reabsorption loss to enhance the optical efficiency of white LED. The 2D island-patterns of QD phosphor film were fabricated using a UV imprinting process and compared the optical efficiency with the other QD film structure prepared with same QD concentrations and thicknesses such as a mixed and separately layered QD structure. Experimental and simulation analysis were performed to confirm the better optical efficiency from the 2D island-patterns of QD films due to the reduced reabsorption loss. High luminescence white LED was finally realized with 2D island-patterns of QD film, resulting in a luminous efficiency of 62.2 lm/W and CRI of 83 with CCT of 4537 K at the operation current of 60 mA.

The recent increased use of mobile phone has resulted in a technical focusing on reliability issues related to drop performance. Since mobile phone may be dropped several times during their use, it is required to survive common drop accidents. The plastic injection parts such as base stopper and carrier in the encoder type actuator can be broken easily in the actual reliability test of 1.5m free drop. So, we analyzed the shock resistance characteristics of auto focus actuator with variables in the material properties using finite element method. By applying the new resin materials, we can decrease the breakage of plastic injection parts and improve the reliability of mobile phone.