Employing CdSexTe1–x Alloyed Quantum Dots to Avoid the Temperature-Dependent Emission Shift of Light-Emitting Diodes

As one of the most promising alternatives in liquid-crystal display backlight, quantum dot light-emitting diodes (QLEDs) exhibit many advantages. However, the inherent thermal sensitivity of quantum dots (QDs) from lattice dilation leads to the temperature-dependent shift of the emission peak, which results in visible color change as great heat is generated during QLED working. To fabricate temperature-independent QLEDs, CdSexTe1–x alloyed QDs are designed and employed as the color conversion materials on GaN LED chips. The key is the adjustment of the energy bandgaps in alloyed QDs. Upon temperature increment, the bandgap between the valence band (VB) and conduction band (CB) increases, while the energy bandgap between the trap state and CB reduces. As a result, the lowered energy of exciton recombination from QD lattice dilation can be offset by the increased energy of trap-related exciton recombination, thus producing the QDs without temperature-dependent emission shift. The LEDs on the basis of CdSexTe1–x QDs are further fabricated, which decreases the temperature-dependent emission shift.