Baruj, Hamed DehghanpourBozkaya, İklimCanımkurbey, BetülIşık, Ahmet TarıkShabani, FarzanDelikanlı, SavaşShendre, S.Erdem, OnurIşık, FurkanDemir, Hilmi Volkan2024-03-182024-03-182023-04-061613-6810https://hdl.handle.net/11693/114907Semiconductor colloidal quantum wells (CQWs) provide anisotropic emission behavior originating from their anisotropic optical transition dipole moments (TDMs). Here, solution-processed colloidal quantum well light-emitting diodes (CQW-LEDs) of a single all-face-down oriented self-assembled monolayer (SAM) film of CQWs that collectively enable a supreme level of IP TDMs at 92% in the ensemble emission are shown. This significantly enhances the outcoupling efficiency from 22% (of standard randomly-oriented emitters) to 34% (of face-down oriented emitters) in the LED. As a result, the external quantum efficiency reaches a record high level 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. This SAM-CQW-LED architecture allows for a high maximum brightness of 19,800 cd m$^{−2}$ with a long operational lifetime of 247 h at 100 cd m$^{−2}$ as well as a stable saturated deep-red emission (651 nm) with a low turn-on voltage of 1.7 eV at a current density of 1 mA cm$^{−2}$ and a high J$_{90}$ of 99.58 mA cm$^{−2}$. These findings indicate the effectiveness of oriented self-assembly of CQWs as an electrically-driven emissive layer in improving outcoupling and external quantum efficiencies in the CQW-LEDs.enCC BY-NC-ND 4.0 DEED (Attribution-NonCommercial-NoDerivs 4.0 International)https://creativecommons.org/licenses/by-nc-nd/4.0/All-solution-processed light-emitting diodes (LEDs)Colloidal quantum wells (CQWs)Colloidal-light-emitting diodes (LEDs)Orientationcontrolled filmsSelf-assemblyArticle10.1002/smll.2022065821613-6829