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Time Resolved Optical Spectroscopy of Colloidal PbS Nanosheets

Neupane, Chandra Prasad, Neupane
http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1530805332385177

Abstract Details

2018, Master of Science (MS), Bowling Green State University, Physics.
Highly luminescent few-atoms thick colloidal PbS nanosheets are a promising material for the applications in infrared optoelectronics and photonics since a large in-plane charge carrier mobility and a tunable energy gap are unified in a single material. The time-resolved photoluminescence of the excitons in the nanosheets shows two distinguished fast and slow decays, which is very different from the quantum dots. The slow decay might be due to the exciton recombination after exciton migration or dissociation. The time-resolved photoluminescence spectroscopy studies show that there is a significant redshift of the emission spectrum later after excitation. This time-dependent photoluminescence spectrum indicates the possible migrations of excitons from thin parts (large energy gaps) of the nanosheets to thick parts (small energy gaps) due to the motion of the charge carriers, or possible Forster resonance energy transfer (FRET) from a thin nanosheet to a thicker one. The shift of the emission spectrum occurs within 500 to 700 nanoseconds, indicating the average time of the exciton-migration or FRET is at the same scale. As a side project of this thesis, the electric dipole moment of a typical PbSe quantum dot in the reaction solution is derived. This helped in the calculation of the dipole-dipole interaction energy of the quantum dots to explain the growth mechanism of PbSe nanorods. Another side project of this thesis was focused on the calculation of the energy gap of the carbon dots consisting amide groups. The calculated energy gap is close to one of the energy gaps measured by optical absorption. It helped to understand the light-emitting mechanism of the carbon dots.
Liangfeng Sun (Advisor)
Alexey Zayak (Committee Member)
Haowen Xi (Committee Member)
62 p.
Physics
Nanoscience; Photophysics; PbS nanosheets; PbSe nanorods; Carbon dots

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Citations

  • Neupane, Neupane, C. P. (2018). Time Resolved Optical Spectroscopy of Colloidal PbS Nanosheets [Master's thesis, Bowling Green State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1530805332385177

    APA Style (7th edition)

  • Neupane, Neupane, Chandra. Time Resolved Optical Spectroscopy of Colloidal PbS Nanosheets. 2018. Bowling Green State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1530805332385177.

    MLA Style (8th edition)

  • Neupane, Neupane, Chandra. "Time Resolved Optical Spectroscopy of Colloidal PbS Nanosheets." Master's thesis, Bowling Green State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1530805332385177

    Chicago Manual of Style (17th edition)

bgsu1530805332385177
338
© 2018, all rights reserved.
This open access ETD is published by Bowling Green State University and OhioLINK.