Quantum Dot LED and Laser
The uniqueness of Quantum Dot LEDs and lasers is that different wavelengths can be achieved by variation of Quantum Dot sizes that isn’t possible using bulk semiconductor LED and laser technology. Also Quantum Dots become very attractive for optoelectronic devices owing to possibility of fabrication of QD LEDs and lasers by roll-to-roll printing and the compatibility with lightweight, flexible plastic substrates that open the potential for low-cost fabrication of large-area flexible devices. Visible QD LED is considered as a next generation display technology after OLED-Displays, exhibits pure color position, high luminance and lower power consumption.
QD LED Fabrication
QD LED can be prepared as follows. The hole transporting layer (HTL) is spin-coated on ITO on a substrate. The substrate can be made of glass or polymer material. Then QDs is deposited by spin-coating. For visible LEDs you can use Perovskite or CdSe/ZnS Quantum Dots. PbS Quantum Dots are for infrared LEDs. Then an electron transporting layer (ETL) and electrodes are deposited using a thermal evaporation system. Electrodes can be prepared from Ag, Au, Al etc.
PbS quantum dots: X. Gong et al. Highly efficient quantum dot near-infrared light-emitting diodes. Nature Photonics. 2016, 10, 253–257; G. J. Supran et al. High-performance shortwave-infrared light-emitting devices using core–shell (PbS–CdS) colloidal quantum dots. Adv. Mater. 2015, 27, 1437–1442.
Perovskite quantum dots: S. Veldhuis. Perovskite Materials for Light-Emitting Diodes and Lasers. Advanced materials. 2016, DOI: 10.1002/adma.201600669; J. Song et al. Quantum dot light-emitting diodes based on Inorganic Perovskite Cesium Lead Halides (CsPbX3). Advanced materials. 2015, 27, 7162–7167.
CdSe/CdS quantum dots: X. Dai et al. Solution-processed, high-performance light-emitting diodes based on quantum dots. Nature. 2014, 515, 96-99; O. Chen et al. Compact high-quality CdSe–CdS core–shell nanocrystals with narrow emission line widths and suppressed blinking. Nature materials. 2013, 12, 445-451.