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Direct Visualization of Exciton Transport in Defective Few‐Layer WS 2 by Ultrafast Microscopy
Author(s) -
Liu Huan,
Wang Chong,
Zuo Zhengguang,
Liu Dameng,
Luo Jianbin
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201906540
Subject(s) - exciton , materials science , diffusion , relaxation (psychology) , ultrafast laser spectroscopy , biexciton , optoelectronics , molecular physics , condensed matter physics , photoluminescence , spectroscopy , chemistry , physics , psychology , social psychology , quantum mechanics , thermodynamics
As defects usually limit the exciton diffusion in 2D transition metal dichalcogenides (TMDCs), the interaction knowledge of defects and exciton transport is crucial for achieving efficient TMDC‐based devices. A direct visualization of defect‐modulated exciton transport is developed in few‐layer WS 2 by ultrafast transient absorption microscopy. Atomic‐scale defects are introduced by argon plasma treatment and identified by aberration‐corrected scanning transmission electron microscopy. Neutral excitons can be captured by defects to form bound excitons in 7.75–17.88 ps, which provide a nonradiative relaxation channel, leading to decreased exciton lifetime and diffusion coefficient. The exciton diffusion length of defective sample has a drastic reduction from 349.44 to 107.40 nm. These spatially and temporally resolved measurements reveal the interaction mechanism between defects and exciton transport dynamics in 2D TMDCs, giving a guideline for designing high‐performance TMDC‐based devices.