Abstract
Quantum dot light-emitting diodes (QLEDs) have been considered as the most promising candidate of light sources for the new generation display and solid-state lighting applications. Especially, the performance of visible QLEDs based on II-VI quantum dots (QDs) has satisfied the requirements of the above applications. However, the optoelectronic properties of the corresponding near-infrared (NIR) QLEDs still lag far behind the visible ones. Here, we demonstrated the highly efficient NIR QLEDs based on chloride treated CdTe/CdSe type-II QDs. The maximum radiant emittance and peak external quantum efficiency (EQE) increased by 24.5 and 26.3%, up to 66 mW/cm2 and 7.2% for the corresponding devices based on the chloride treated CdTe/CdSe QDs with the PL peak located at 788 nm, respectively, compared with those of devices before chloride treatment. Remarkably, the EQE of > 5% can be sustained at the current density of 0.3–250 mA/cm2 after the chloride treatment. Compared with NIR LEDs based on transition metal complex, the efficiency roll-off has been suppressed to some extent for chloride treated CdTe/CdSe based NIR QLEDs. Based on the optimized conditions, the peak EQE of 7.4, 5.0, and 1.8% can be obtained for other devices based on chloride treated CdTe/CdSe with PL peak of 744, 852, and 910 nm, respectively. This improved performance can be mainly attributed to the chloride surface ligand that not only increases the carrier mobility and reduces the carrier accumulation, but also increases the probability of electron-hole radiative efficiency within QD layers.
Highlights
Near-infrared (NIR) light-emitting diodes (LEDs) have a rapid development in last decades, because their foreseeable great potential for applications in bio-imaging and clinical diagnosis, night-vision equipments, fiber-optic communications, and computing (Graham et al, 2011; Sun et al, 2012; Dai et al, 2017; Panfil et al, 2018; Song E. et al, 2019)
In order to further explore the evolution of crystal structures of CdTe/CdSe core/shell quantum dots (QDs), their phase and crystallographic properties were investigated by X-ray diffractometer (XRD) (Supplementary Figure 2)
We have demonstrated highly efficient NIR Quantum dot light-emitting diodes (QLEDs) based on chloride treated CdTe/CdSe type-II QDs
Summary
Near-infrared (NIR) light-emitting diodes (LEDs) have a rapid development in last decades, because their foreseeable great potential for applications in bio-imaging and clinical diagnosis, night-vision equipments, fiber-optic communications, and computing (Graham et al, 2011; Sun et al, 2012; Dai et al, 2017; Panfil et al, 2018; Song E. et al, 2019). The peak external quantum efficiency (EQE) of NIR light sources based on transition metal complex (such as osmium, iridium, and platinum), organic LEDs (OLEDs) and perovskite LEDs (PeLEDs) has been up to > 9%, 10% (at 721 nm), and even more than 20% (20.7% at 803 nm, and 21.6% at 800 nm), Highly Efficient Near-Infrared CdTe/CdSe-Based QLEDs respectively (Graham et al, 2011; Cao et al, 2018; Kim et al, 2018; Xu et al, 2019). CdTe/CdSe type-II QDs can be extended into the NIR region along with high PL QY and good stability, due to the higher energies of valence and conduction bands of the core than those of the shell (Kim et al, 2003; Shea-Rohwer et al, 2013), which make them kind of the most promising NIR materials
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
