Orientation-Dependent Photoconductivity of Quasi-2D Nanocrystal Self-Assemblies: Face-Down, Edge-Up Versus Randomly Oriented Quantum Wells.

Autor: Ibrahem MA; Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology and The National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey.; Laser Science and Technology Branch, Applied Sciences Department, University of Technology, Baghdad, 10066, Iraq., Waris M; Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology and The National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey., Miah MR; Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology and The National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey., Shabani F; Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology and The National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey., Canimkurbey B; Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology and The National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey.; Serefeddin Health Services Vocational School, Central Research Laboratory, Amasya University, Amasya, 05100, Turkey., Unal E; Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology and The National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey., Delikanli S; Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology and The National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey., Demir HV; Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology and The National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey.; Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore.
Jazyk: angličtina
Zdroj: Small (Weinheim an der Bergstrasse, Germany) [Small] 2024 Jul; Vol. 20 (30), pp. e2401423. Date of Electronic Publication: 2024 May 21.
DOI: 10.1002/smll.202401423
Abstrakt: Here, strongly orientation-dependent lateral photoconductivity of a CdSe monolayer colloidal quantum wells (CQWs) possessing short-chain ligands is reported. A controlled liquid-air self-assembly technique is utilized to deliberately engineer the alignments of CQWs into either face-down (FO) or edge-up (EO) orientation on the substrate as opposed to randomly oriented (RO) CQWs prepared by spin-coating. Adapting planar configuration metal-semiconductor-metal (MSM) photodetectors, it is found that lateral conductivity spans ≈2 orders of magnitude depending on the orientation of CQWs in the film in the case of utilizing short ligands. The long native ligands of oleic acid (OA) are exchanged with short-chain ligands of 2-ethylhexane-1-thiol (EHT) to reduce the inter-platelet distance, which significantly improved the photoresponsivity from 4.16, 0.58, and 4.79 mA W -1 to 528.7, 6.17, and 94.2 mA W -1 , for the MSM devices prepared with RO, FO, and EO, before and after ligands exchange, respectively. Such CQW orientation control profoundly impacts the photodetector performance also in terms of the detection speed (0.061 s/0.074 s for the FO, 0.048 s/0.060 s for the EO compared to 0.10 s/0.16 s for the RO, for the rise and decay time constants, respectively) and the detectivity (1.7 × 10 10 , 2.3 × 10 11 , and 7.5 × 10 11 Jones for the FO, EO, and RO devices, respectively) which can be further tailored for the desired optoelectronic device applications. Attributed to charge transportation in colloidal films being proportional to the number of hopping steps, these findings indicate that the solution-processed orientation of CQWs provides the ability to tune the photoconductivity of CQWs with short ligands as another degree of freedom to exploit and engineer their absorptive devices.
(© 2024 The Authors. Small published by Wiley‐VCH GmbH.)
Databáze: MEDLINE
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