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Managing the Surface of Infrared Colloidal Quantum Dots for Photovoltaics.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Managing the Surface of Infrared Colloidal Quantum Dots for Photovoltaics./
Author:	Fan, James Zhangming.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2020,
Description:	157 p.
Notes:	Source: Dissertations Abstracts International, Volume: 82-06, Section: B.
Contained By:	Dissertations Abstracts International82-06B.
Subject:	Electrical engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28148587
ISBN:	9798698550488

Managing the Surface of Infrared Colloidal Quantum Dots for Photovoltaics.
Fan, James Zhangming.

Managing the Surface of Infrared Colloidal Quantum Dots for Photovoltaics. - Ann Arbor : ProQuest Dissertations & Theses, 2020 - 157 p.

Source: Dissertations Abstracts International, Volume: 82-06, Section: B.

Thesis (Ph.D.)--University of Toronto (Canada), 2020.

This item must not be sold to any third party vendors.

Colloidal quantum dots (CQDs) are a thin film technology that has been used in optoelectronic devices such as lasers, light emitting diodes, photodetectors, and solar cells. CQDs exhibit size-dependent absorption and are capable of harvesting light beyond the bandedge of many traditional semiconducting materials, making them of interest as the back cell in multijunction solar cells. Specifically, using CQDs with an exciton peak positioned beyond 1100 nm – IR-CQDs – allows short-wave infrared (SWIR) absorption beyond silicon’s bandgap.The aim of this thesis is to understand how passivation is achieved in IR-CQDs; and to use these insights to create IR-CQDs that advance IR harvesting performance. The crucial performance metric to be advanced is IR power conversion efficiency (IR-PCE) – the power points added by harvesting light transmitted by a silicon solar cell.I began by tackling the problem of improving CQD colloidal stability, an advance necessary to the fabrication of high-quality films. I developed a halide re-shelling exchange that stabilizes the IR-CQDs in polar solvents. The resulting solar cells increased the IR-PCE to 0.76%, greater than the IR-PCE of 0.4% achieved in the best previously-reported ink-based IR-CQD solar cells.Different halide passivants were the focus of my next effort. Using a mixed lead halide (MPbX) PbS ligand exchange, I improved both passivation and transport in CQD solar cells. MPbX-PbS solar cells reached an external quantum efficiency (EQE) of 80% at their exciton at 1210 nm and an IR-PCE of 1.17%.I then went on to study how smaller-bandgap (0.7 eV) IR-CQDs could be used to fabricate solar cells. A blade coating strategy was developed to fabricate micrometer thick films capable of harvesting 60% of available solar photons. The resulting IR-CQD solar cell reached an EQE exciton peak of 80% at 1670 nm, resulting in a record IR-PCE of 1.57%.This thesis presents a suite of strategies to passivate IR-CQDs. The techniques developed in this work offer routes to liquid-processed optoelectronic devices in solar energy and beyond.

ISBN: 9798698550488Subjects--Topical Terms:

596380
Electrical engineering.
Subjects--Index Terms:

Infrared

Managing the Surface of Infrared Colloidal Quantum Dots for Photovoltaics.
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500 $a Source: Dissertations Abstracts International, Volume: 82-06, Section: B.
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520 $a Colloidal quantum dots (CQDs) are a thin film technology that has been used in optoelectronic devices such as lasers, light emitting diodes, photodetectors, and solar cells. CQDs exhibit size-dependent absorption and are capable of harvesting light beyond the bandedge of many traditional semiconducting materials, making them of interest as the back cell in multijunction solar cells. Specifically, using CQDs with an exciton peak positioned beyond 1100 nm – IR-CQDs – allows short-wave infrared (SWIR) absorption beyond silicon’s bandgap.The aim of this thesis is to understand how passivation is achieved in IR-CQDs; and to use these insights to create IR-CQDs that advance IR harvesting performance. The crucial performance metric to be advanced is IR power conversion efficiency (IR-PCE) – the power points added by harvesting light transmitted by a silicon solar cell.I began by tackling the problem of improving CQD colloidal stability, an advance necessary to the fabrication of high-quality films. I developed a halide re-shelling exchange that stabilizes the IR-CQDs in polar solvents. The resulting solar cells increased the IR-PCE to 0.76%, greater than the IR-PCE of 0.4% achieved in the best previously-reported ink-based IR-CQD solar cells.Different halide passivants were the focus of my next effort. Using a mixed lead halide (MPbX) PbS ligand exchange, I improved both passivation and transport in CQD solar cells. MPbX-PbS solar cells reached an external quantum efficiency (EQE) of 80% at their exciton at 1210 nm and an IR-PCE of 1.17%.I then went on to study how smaller-bandgap (0.7 eV) IR-CQDs could be used to fabricate solar cells. A blade coating strategy was developed to fabricate micrometer thick films capable of harvesting 60% of available solar photons. The resulting IR-CQD solar cell reached an EQE exciton peak of 80% at 1670 nm, resulting in a record IR-PCE of 1.57%.This thesis presents a suite of strategies to passivate IR-CQDs. The techniques developed in this work offer routes to liquid-processed optoelectronic devices in solar energy and beyond.
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