Cd-Free Quantum Dots Synthesis with QLED Applcation
▶ Background and Motivation
Display Research forecasts the overall QD display component, lighting and QLED market will reach $10.8 billion by 2026. Cadmium based QDs are most efficient in terms of color purity and quantum yield. But the use of Cd and other heavy metals (Pb and Hg) in electrical and electronic equipment (EEE) is restricted by the EU’s RoHS legislation (max. permitted concentration of Cd is 0.01 wt.% (100ppm)).
▶ Cadmium free QDs
Indium phosphide (InP) is one of the most promising Cd-free QD due to its emission tunability ranging from visible to near-infrared region. Typical InP QDs have emission peak full width at half maximum (FWHM) values around 45-50 nm and quantum yields (QYs) up to 70%. The FWHM and QYs need to be improved in order to apply in display applications.
▶ InP QDs Synthesis and Characterization
Addition of Zn precursor during the core synthesis, eliminated the negative effect of the Zn precursor addition to the pre-synthesized InP core and decreased the emission FWHM. By changing the indium to palmitic acid or phosphorus ratio, it is possible to synthesis InP QDs emitting from 488 to 550 nm with FWHM less than 40 nm.
▶ InP QLED Application & Patterning Process
A quantum dot Light Emitting Diode (QD-LED) is an electro-emissive quantum dot display device that uses quantum dot (QD) as active layer which can produce pure monochromatic red, green, and blue light. AMQLED displays will use electroluminescent QD nanoparticles functioning as QD-LED arranged in an active matrix array. Electroluminiscent quantum dot displays are an experimental type of new display based on quantum-dot light-emitting diodes (QLED, QD-LED). These displays are similar to active-matrix organic light-emitting diode (AMOLED) and micro-LED displays, in that light would be produced directly in each pixel by applying electric current to inorganic QDs. QD-LED displays could support large, flexible displays and would not degrade as readily as OLEDs, making them good candidates for flat-panel TV screens, digital cameras, mobile phones etc. (https://en.wikipedia.org/wiki/Quantum_dot_display)
Our group is studying the core technologies of new materials and devices to develop high efficiency QLED using environmentally friendly Cd-Free QDs