54.1: Invited Paper: Highly efficient Quantum Rods LEDs for LCD backlights

Abstract

Efficient white LEDs with efficacy of > 200 lm/W are much desirable for lighting and displays. LCDs is the market leader with an approximate 70% market share, particularly in the medium‐ to large‐size display segment. The largest portion of power consumption for LCDs belongs to LCD backlight, accounting for 70%–80% of the total power consumption, which strongly depends on the content and resolution of display panels. [1–8] The polarizer and color filters are the two main components responsible for high‐power consumption. Although the phosphor‐based LED backlights are much more efficient than the CCFL backlight, the efficiency of display backlight LEDs varies in the range of 70–85 lm/W. A large portion of the phosphor‐based LED light is lost in color filters [1–5]. The LED efficacy further decreases at the high brightness required for outdoor applications [4]. Intensive efforts have been made to replace the phosphor with quantum dots‐based downconverters, but the efficiency and stability of these devices are still in their infancy. Quantum rods (QRs), the elongated shape nanoparticles, show superior properties such as relatively larger Stokes shifts, polarized emission, and high light out‐coupling efficiency in the solid‐state. The challenges are as follows: 1. high quantum yield of QRs in the thin solid films covering the whole visible range; 2. good in‐plane alignment of the QRs on the LEDs; and 3. high photo‐stability and low‐temperature quenching. In this talk, we will try to discuss all these challenges. We will also discuss the merits of gradient alloyed CdSe/ZnXCd1‐XS/ZnS and CdSe/CdS/ZnS core/shell/shell QRs downconverters showing high efficacy LEDs covering a wide color gamut. These QRs‐based LEDs attain the luminous efficacy (LE) of 149 lm/W (@10mA), wide color gamut (118% NTSC), which is exceedingly higher than the state‐of‐the‐art quantum dot and phosphor‐based on‐chip LED, which paves the way for the future display backlight with the efficacy of > 200 lm/W.