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Title: Observation of Negative Photoconductivity in Lead-Free Cs3Bi2Br9Perovskite Single Crystal
Authors: Tailor N.K.
Maity P.
Satapathi, Soumitra
Published in: ACS Photonics
Abstract: Light exposure usually causes an increase in photoconductivity in perovskite semiconductors. However, we report here light-induced negative photoconductivity, followed by slow dark self-recovery in a lead-free Cs3Bi2Br9 perovskite single crystal. Femtosecond transient reflection (fs-TR) spectroscopy studies further reveal hole self-trapping at the Vk center (Br2- dimer) in the midband states of this vacancy-ordered perovskite. Subsequently, these charged defect states (Vk) trap photogenerated charge carriers and produce an internal electrical field, which essentially opposes the externally applied field, leading to negative photoconductivity. A highly sensitive prototype photodetector was fabricated with figure of merits estimated as responsivity (6.42 mA/W), detectivity (2.51 × 1012 Jones), and current in a dark to light ratio (∼20). Our observation of this retrospective photocurrent in optically active perovskite materials can be applied for developing highly sensitive detectors. © 2021 American Chemical Society.
Citation: ACS Photonics, 8(8): 2473-2480
Issue Date: 2021
Publisher: American Chemical Society
Keywords: hole self-trapping
negative photoconductivity
perovskite single crystal
transient reflection spectroscopy
ISSN: 23304022
Author Scopus IDs: 57211634045
Author Affiliations: Tailor, N.K., Department of Physics, Indian Institute of Technology Roorkee, Uttarakhand, Roorkee, 247667, India
Maity, P., Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
Satapathi, S., Department of Physics, Indian Institute of Technology Roorkee, Uttarakhand, Roorkee, 247667, India
Funding Details: S.S. acknowledges the ISRO Research Grant (STC-1563-PHY). N.K.T. is thankful for the UGC fellowship. Indian Space Research Organisation, इसरो: STC-1563-PHY; University Grants Committee, UGC
Corresponding Author: Satapathi, S.; Department of Physics, Uttarakhand, India; email:
Appears in Collections:Journal Publications [PH]

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