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Title: Ultrafast control of the optical transition in type-II colloidal quantum wells
Authors: Yu, Junhong
Durmusoglu, Emek Goksu
Wang, Yimeng
Sharma, Manoj
Demir, Hilmi Volkan
Dang, Cuong
Keywords: Physics
Issue Date: 2023
Source: Yu, J., Durmusoglu, E. G., Wang, Y., Sharma, M., Demir, H. V. & Dang, C. (2023). Ultrafast control of the optical transition in type-II colloidal quantum wells. ACS Photonics, 10(5), 1250-1258.
Project: MOE- T2EP50121-0012 
Journal: ACS Photonics 
Abstract: Manipulating the optical transition in semiconductors at ultrashort timescales is of both fundamental interest and central importance for emerging photonic applications. Traditionally, this manipulation is realized by electrostatic gating via Stark effects or band-gap renormalizations. Here, we report an ultrafast and all-optical route to engineer an indirect transition in core-crown colloidal quantum wells (CQWs), namely, CdSe/CdTe, with a type-II band alignment. Following the intense laser pulse excitation, the indirect band transition energy exhibits a pronounced blueshift-redshift crossover on the picosecond timescale, stemming from the formation and dissipation of the transient electric field (E-field) that forms upon photoexcitation to compensate for the driving force provided by the band offsets. Both the energy shift and dynamics of the transient E-field can be modulated optically by tuning the laser pulse excitation fluence. Our finding demonstrates a strong analogy between the type-II heterojunction and a p-n junction with respect to carrier equilibrium processes, which holds promise to facilitate the integration of CQWs within optical switching networks.
ISSN: 2330-4022
DOI: 10.1021/acsphotonics.2c01799
Schools: School of Physical and Mathematical Sciences 
School of Electrical and Electronic Engineering 
Research Centres: LUMINOUS! Centre of Excellence for Semiconductor Lighting & Displays 
The Photonics Institute 
CNRS International NTU THALES Research Alliances 
Rights: © 2023 American Chemical Society. All rights reserved. This article may be downloaded for personal use only. Any other use requires prior permission of the copyright holder. The Version of Record is available online at
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:SPMS Journal Articles

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