Observation of Negative Photoconductivity in Lead-Free Cs3Bi2Br9Perovskite Single Crystal
KAUST DepartmentKAUST Solar Center (KSC)
KAUST Catalysis Center (KCC)
Physical Science and Engineering (PSE) Division
Embargo End Date2022-07-21
Permanent link to this recordhttp://hdl.handle.net/10754/670287
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AbstractLight 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.
CitationTailor, N. K., Maity, P., & Satapathi, S. (2021). Observation of Negative Photoconductivity in Lead-Free Cs3Bi2Br9Perovskite Single Crystal. ACS Photonics. doi:10.1021/acsphotonics.1c00702
SponsorsS.S. acknowledges the ISRO Research Grant (STC-1563-PHY). N.K.T. is thankful for the UGC fellowship.
PublisherAmerican Chemical Society (ACS)