Related Experiment Video
Updated: Jul 3, 2026
10:40
High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy
Published on: June 28, 2016
Confinement-dependent below-gap state in PbS quantum dot films probed by continuous-wave photoinduced absorption
The Journal of Physical Chemistry. B
|July 19, 2008
Summary
We measured photoinduced absorption in PbS quantum dots, revealing a below-gap state transition. This transition, dependent on quantum dot size, could monitor charge transfer.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Investigated continuous-wave (cw) photoinduced absorption (PA) spectra in PbS quantum dot (QD) films.
- Studied four different QD sizes across a 0.25-0.5 eV spectral range at 10 K.
Discussion:
- Observed a strong, asymmetric infrared photoinduced absorption (IR-PA) peak.
- Analyzed the confinement dependence of the IR-PA peak position and shape.
- Interpreted the IR-PA as a transition from a below-gap state to the second excitonic level (1P), supported by interband transition and Stokes shift data.
Key Insights:
- The below-gap state exhibits a lifetime of several microseconds, determined by frequency-dependent IR-PA measurements.
- Provided potential explanations for the origin of this below-gap state.
- Highlighted the potential application of this transition for monitoring photogenerated charge transfer in QD systems.
Outlook:
- Further research into the precise origin of the below-gap state is warranted.
- Exploration of this transition for practical applications in charge transfer monitoring.
- Investigating the influence of other parameters on the below-gap state and its transition properties.
