TY - JOUR AU - Chung, Dong Seob AU - Davidson‑Hall, Tyler AU - Cotella, Giovanni AU - Lyu, Quan AU - Chun, Peter AU - Aziz, Hany PY - 2022/11/04 Y2 - 2024/03/29 TI - Significant Lifetime Enhancement in QLEDs by Reducing Interfacial Charge Accumulation via Fluorine Incorporation in the ZnO Electron Transport Layer JF - Nano-Micro Letters JA - Nano-Micro Lett VL - 14 IS - SE - Articles DO - 10.1007/s40820-022-00970-x UR - https://nmlett.org/index.php/nml/article/view/1209 SP - 212 AB - <p>ZnO nanoparticles are widely used for the electron transport layers (ETLs) of quantum dots light emitting devices (QLEDs). In this work we show that incorporating fluorine (F) into the ZnO ETL results in significant enhancement in device electroluminescence stability, leading to LT50 at 100&nbsp;cd&nbsp;m<sup>−2</sup> of 2,370,000&nbsp;h in red QLED, 47X longer than the control devices. X-ray photo-electron spectroscopy, time-of-flight secondary ion mass spectroscopy, photoluminescence and electrical measurements show that the F passivates oxygen vacancies and reduces electron traps in ZnO. Transient photoluminescence versus bias measurements and capacitance–voltage-luminance measurements reveal that the CF<sub>4</sub> plasma-treated ETLs lead to increased electron concentration in the QD and the QD/hole transport layer interface, subsequently decreasing hole accumulation, and hence the higher stability. The findings provide new insights into the critical roles that optimizing charge distribution across the layers play in influencing stability and present a novel and simple approach for extending QLED lifetimes.</p><p>Highlights:</p><p>1 Quantum dots light emitting devices (QLEDs) with extremely long half-lifetimes at 100 cd m<sup>−2</sup>, 2,370,000 h were successfully fabricated using CF<sub>4</sub> plasma-treated ZnO nanoparticle electron transport layers.<br>2 A new experimental approach that probes changes in exciton lifetime under current flow was used to investigate the changes in carrier concentration in QLEDs.<br>3 Evidence of the dependence of QLED stability on electron and hole concentrations at the QD/HTL interface was revealed.</p> ER -