Enhancing the Performance of Light-Emitting Electrochemical Cells by Incorporating Quantum Dots

Light-emitting electrochemical cells (LECs) are one of the most promising technologies for solid-sate lighting and display. We present a hybrid device concept for achieving higher performance by combining red colloidal quantum dots (QDs) and Ir-based ionic transition metal complex (iTMC). The utilized QDs exhibit a core–shell structure of CdSe/ZnS. By this method, the resultant devices exhibit a maximum luminance of 14 383 cd/m $^{\text{2}}$ and current efficiency (CE) of 2.00 cd/A, almost fourfold higher than those (3475 cd/m $^{\text{2}}$ and 0.55 cd/A) of the control device. In conclusion, QDs exert a regulatory effect on charge carrier transport in hybrid devices, gradually aligning the electron and hole injection of the device, thus enhancing its performance. Red QD (RQD) not only has an electron injection buffering effect but also plays a certain role in hole blocking.