2022/01/21 by Hamed Dehghanpour Baruj, Baruj, Hamed Dehghanpour, Yurdakul, Iklim +16
Engineering · Materials Science · Physics and Astronomy · #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Nonlinear Optical Materials Studies #Optics (physics.optics) #Photonic Crystals and Applications #Quantum Dots Synthesis And Properties
paper · pdf · doi:10.48550/arxiv.2201.08733
openalex publication_date 2022/01/21 · openalex created_date 2022/04/03 · openalex updated_date 2026/07/28
Semiconductor colloidal quantum wells (CQWs) make an exciting quasi-2D class of nanocrystals thanks to their unique properties including their highly anisotropic optical transition dipole moment (TDM). Thus, employing a film of CQWs with face-down orientation as an emissive layer (EML) in an electroluminescent device is expected to substantially boost photon outcoupling efficiency. Here, we show all-solution-processed colloidal quantum well light-emitting diodes (CQW-LEDs) using a single all-face-down oriented self-assembled monolayer (SAM) film of CQWs that enables a high level of in-plane (IP) TDMs of 92%. This SAM film significantly enhances the outcoupling efficiency from 22% (of standard randomly-oriented emitters) to 34% (of face-down oriented emitters) and charge injection efficiency. This SAM-CQW-LED architecture enables a record high level of external quantum efficiency of 18.1% for the solution-processed type of CQW-LEDs, putting their efficiency performance on par with the hybrid organic-inorganic evaporation-based CQW-LEDs and all other best solution-processed LEDs. In addition, this architecture provides a high maximum brightness of 19,800 cd/m2 with a long operational lifetime of 247 h at 100 cd/m2 along with saturated deep-red emission (651 nm). These findings indicate the effectiveness of oriented self-assembly of CQWs as electrically-driven emissive layers in improving outcoupling and external quantum efficiencies in the CQW-LEDs.