83‐3: Electron Transportation Engineering for Record High External Quantum Efficiency of 16.8% for Quantum Rod Light‐Emitting Diodes

The semiconductor quantum rods (QRs) offer unique benefits that differ from the spherical QDs, such as linearly polarized light and higher light outcoupling efficiency, which can double the external quantum efficiency of the light‐emitting diodes (LEDs). Despite having many potential advantages, the QRs are not well explored as QDs in electroluminescent LEDs. In this work, we synthesized CdSe/CdS QRs and verified them in QR‐based LEDs. The charge injection into the QRLEDs is precisely controlled to get the maximum charge balance in the device to improve the device's efficiency. We achieved an EQE of 16.8 %, which is the highest EQE reported for QRLEDs. The turn‐on voltage, peak luminance, and current efficiency (CE) of the QRLEDs are 2.2 V, 10000 cd/m 2 , and 11.6 %, respectively. The electron injection does not influence the device turn‐on voltage but severely impacts the QRLEDs brightness, EQE and CE. The spin coated QRs film has small voids on the surface, which needs to be optimized further to improve the QRLEDs efficiency. Overall, these findings have insightful information on QRLEDs fabrication, which can open up a new opportunity for device applications.