Highly Bright Top-Emitting Quantum Dot Light-Emitting Diodes Fabricated on Si Substrate

Quantum dot light-emitting diodes (QLEDs) are one of the most promising candidates for next generation display due to their advantages such as high photoluminescence quantum yield (PL QY), narrow bandwidth, and facile color tunability of quantum dot (QD) materials. Although the performance of QLEDs have been improved significantly, they are exclusively optimized for the display brightness since those QLEDs are usually vulnerable to high electrical or thermal stress. For QLEDs to exhibit higher luminance (<i>L</i>), therefore, it is important to resolve those degradation issues at an intense operating condition. Here, we demonstrate ultra-bright QLEDs by adopting multi-lateral approaches—from the synthesis of QD materials to the elaborate engineering of the device structure. First, the non-radiative Auger recombination under high current densities (<i>J</i>) is effectively suppressed by tailoring the core/shell interfaces of QDs. Second, the top-emission device structure is optimized based on optical simulation to enhance the light outcoupling. Finally, the thermally conductive Si substrate is used to dissipate thermal energies at high <i>J</i>. Combining these approaches, our red top-emitting QLEDs exhibit unprecedently high maximum <i>L</i> and the current efficiency, which exceed 3,000,000 cd m⁻² and 75 cd A⁻¹ respectively. We believe that our breakthrough can make QLEDs explore to other diversified and specialized fields, such as lighting source, laser diode, or photo-medical therapy.