UC Irvine

Light Emitting Diodes (LEDs) are the most beneficial optoelectronic devices for human lives. LEDs already dominated mainstream lightings market, not only the general lightings but also displays, medical applications, and so on, to replace conventional light sources due to their small forma factors and high efficiency. Extensive researches have been carried out ever since introduced, and reported significant enhancement in optical output for the individual LED chip, and it is also pointed out that the enhancement in optical output for the emitter and the lighting system level must be considered by improvement of packaging materials and processes. In addition, the requirement for wide color gamut as well as enhanced optical output has been more important to be applied for color displays such as liquid crystal displays (LCDs). This dissertation is focused on addressing two parts, to propose optimized packaging designs of LED emitters and displays based on the points mentioned above.

First, an optimized design of packaging materials and process of enhancement in optical output of individual LED emitters is proposed using transparent die bonding material considering optical characteristics. It is shown that the optically transparent die attach adhesive prevent light absorption from the LED chip so that a substantial amount of light output of blue and phosphor converted white LED emitters compared to the conventional LED emitters using silver (Ag) based die bonding material. This optimization includes surface mount device (SMD) and chip-on-board (COB) type LED emitters. In addition to the COB-LED emitters, a transparent substrate is also shown to enhance light output and able to form an omnidirectional LED emitter.

Second, optimized packaging designs for color conversion film are proposed for wide color gamut displays. It is shown that the converted peak wavelengths by using quantum dot (QD) materials from blue backlights are well tuned and matched with required color coordinates for LCDs with a wide color gamut. A dichroic filter applied on the color conversion film dramatically reduced the amount of QD materials required by recycling excessive blue emission. More advanced packaging design for the color conversion film as pixels is also studied to replace color filters not only for LCDs but also for OLEDs.