Highly-directional, highly-efficient solution-processed light-emitting diodes of all-face-down oriented colloidal quantum wells
Abstract
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.
Keywords
Cite
@article{arxiv.2201.08733,
title = {Highly-directional, highly-efficient solution-processed light-emitting diodes of all-face-down oriented colloidal quantum wells},
author = {Hamed Dehghanpour Baruj and Iklim Yurdakul and Betul Canimkurbey and Ahmet Tarik Isik and Farzan Shabani and Savas Delikanli and Sushant Shendre and Onur Erdem and Furkan Isik and Hilmi Volkan Demir},
journal= {arXiv preprint arXiv:2201.08733},
year = {2022}
}