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Thin Film PbS Quantum Dot Solar Cells

Duff, Matthew (2020) Thin Film PbS Quantum Dot Solar Cells. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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The charge carrier kinetics of P and N type Lead sulfide quantum dots were examined to determine metrics for both hole and electron transport during solar cell operation. This was achieved by using a dual illumination scheme to excite the solar cell through front and back transparent contacts. By changing the illumination direction, the distances hole and electrons travel will also be switched. This allows us to measure the carrier kinetics of the farthest moving charge carrier during solar cell operation. Using JV, IPCE, and current decay measurements, this study found that hole and electron transport in N type PbS is symmetrical and in P type PbS, electron transport suffers compared to hole transport. With the addition of a P/N junction between the two quantum dot layers, the transit times for both holes and electrons decreased significantly with large improvements in electron transport in P type PbS.
Tamm surface plasmons were also investigated to determine their effect on the optoelectronic properties of PbS quantum dot solar cells. Tamm surface plasmons are created when a Bragg mirror is in conjunction with a thin metal film. Strong plasmonic resonances occur in the metal film for photons with the same wavelength as the Bragg mirror. When put in conjunction with a PbS solar cell, the plasmonic film enhanced the light absorption of the device leading to more photon absorption and charge generation, improving the efficiency of the PbS quantum dot solar cell. Light absorption was improved through near and far field plasmonic effects. Near field effects coupled light to the gold film greatly increasing the optical cross section of PbS near the thin film for photons near the Bragg wavelength of the Tamm plasmon substrate. Far field reflectance effects also enhanced the photon optical pathway to allow for a higher probability of light absorption. Different wavelength of light can be targeted by the Tamm surface plasmon effect by changing the dielectric layer thicknesses of the underlying Bragg mirror. The body of this work can be applied to other solar cell types to acquire qualitative information on hole and electron transport to improve the design of devices. Tamm surface plasmons are an understudied top in the field of plasmonic assisted solar cell design and this paper can act as a stepping stone for future research.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Duff, Matthewmld92@pitt.edumld920000-0001-8175-1591
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Thesis AdvisorLee, JKjul37@pitt.eduJUL370000-0002-7778-7679
Committee MemberNettleship, Iannettles@pitt.eduNETTLES
Committee MemberChmielus, MarkusCHMIELUS@pitt.eduCHMIELUS
Committee MemberYun, MinheeMIY16@pitt.eduMIY16
Date: 29 January 2020
Date Type: Publication
Defense Date: 8 November 2019
Approval Date: 29 January 2020
Submission Date: 19 November 2019
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 125
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Materials Science and Engineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Solar Cells, Plasmonics, Surface plasmons, Tamm surface plasmons, Charge kinetics
Date Deposited: 29 Jan 2020 16:55
Last Modified: 29 Jan 2020 16:55


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