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Title: Carbon Nanotubes for Quantum Dot Photovoltaics with Enhanced Light Management and Charge Transport

Abstract

Colloidal quantum dot (CQD)-based photovoltaics are an emerging low-cost solar cell technology with power conversion efficiencies exceeding 10%, i.e., high enough to be interesting for commercialization. Well-controlled and understood charge carrier transport through the device stack is required to make the next step in efficiency improvements. In this work, polymer-wrapped single-walled carbon nanotube (SWNT) films embedded in an insulating poly(methyl methacrylate) (PMMA) matrix and capped by a thermally evaporated Au electrode are investigated as a composite hole transport layer and optical spacer. Employing transient absorption spectroscopy we show that the SWNTs enhance the charge transfer rate from CQD to CQD, ZnO, or SWNT. In order to pinpoint the underlying mechanism for the improvement, we investigate the energetics of the junction by measuring the relative alignment of the band edges, using Kelvin probe and cyclic voltammetry. Measuring the external quantum efficiency and absorption we find that the improvement is not mainly from electronic improvements but from enhanced absorption of the CQD absorber. We demonstrate experimentally and theoretically, by employing a transfer-matrix model, that the transparent PMMA matrix acts as an optical spacer, which leads to an enhanced absorption in the absorber layer. Lastly, with these electronic and optical enhancements, the efficiencymore » of the PbS CQD solar cells improved from 4.0% to 6.0%.« less

Authors:
 [1];  [2];  [1];  [1];  [3];  [1];  [1];  [1];  [1];  [3];  [1];  [1]
  1. Univ. of Oxford (United Kingdom)
  2. Univ. of Oxford (United Kingdom); National Renewable Energy Lab. (NREL), Golden, CO (United States)
  3. Universidade Estadual de Campinas, Rua Sérgio Buarque de Holanda (Brazil)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1489327
Report Number(s):
NREL/JA-5900-73019
Journal ID: ISSN 2330-4022
Grant/Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ACS Photonics
Additional Journal Information:
Journal Volume: 5; Journal Issue: 12; Journal ID: ISSN 2330-4022
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; charge carrier transfer; colloidal quantum dots; hole transport layer; optical spacer effect; photovoltaics; single-walled carbon nanotube

Citation Formats

Tazawa, Yujiro, Habisreutinger, Severin N., Zhang, Nanlin, Gregory, Daniel A. F., Nagamine, Gabriel, Kesava, Sameer V., Mazzotta, Giulio, Assender, Hazel E., Riede, Moritz, Padilha, Lazaro A., Nicholas, Robin J., and Watt, Andrew A. R.. Carbon Nanotubes for Quantum Dot Photovoltaics with Enhanced Light Management and Charge Transport. United States: N. p., 2018. Web. doi:10.1021/acsphotonics.8b00982.
Tazawa, Yujiro, Habisreutinger, Severin N., Zhang, Nanlin, Gregory, Daniel A. F., Nagamine, Gabriel, Kesava, Sameer V., Mazzotta, Giulio, Assender, Hazel E., Riede, Moritz, Padilha, Lazaro A., Nicholas, Robin J., & Watt, Andrew A. R.. Carbon Nanotubes for Quantum Dot Photovoltaics with Enhanced Light Management and Charge Transport. United States. doi:10.1021/acsphotonics.8b00982.
Tazawa, Yujiro, Habisreutinger, Severin N., Zhang, Nanlin, Gregory, Daniel A. F., Nagamine, Gabriel, Kesava, Sameer V., Mazzotta, Giulio, Assender, Hazel E., Riede, Moritz, Padilha, Lazaro A., Nicholas, Robin J., and Watt, Andrew A. R.. Thu . "Carbon Nanotubes for Quantum Dot Photovoltaics with Enhanced Light Management and Charge Transport". United States. doi:10.1021/acsphotonics.8b00982.
@article{osti_1489327,
title = {Carbon Nanotubes for Quantum Dot Photovoltaics with Enhanced Light Management and Charge Transport},
author = {Tazawa, Yujiro and Habisreutinger, Severin N. and Zhang, Nanlin and Gregory, Daniel A. F. and Nagamine, Gabriel and Kesava, Sameer V. and Mazzotta, Giulio and Assender, Hazel E. and Riede, Moritz and Padilha, Lazaro A. and Nicholas, Robin J. and Watt, Andrew A. R.},
abstractNote = {Colloidal quantum dot (CQD)-based photovoltaics are an emerging low-cost solar cell technology with power conversion efficiencies exceeding 10%, i.e., high enough to be interesting for commercialization. Well-controlled and understood charge carrier transport through the device stack is required to make the next step in efficiency improvements. In this work, polymer-wrapped single-walled carbon nanotube (SWNT) films embedded in an insulating poly(methyl methacrylate) (PMMA) matrix and capped by a thermally evaporated Au electrode are investigated as a composite hole transport layer and optical spacer. Employing transient absorption spectroscopy we show that the SWNTs enhance the charge transfer rate from CQD to CQD, ZnO, or SWNT. In order to pinpoint the underlying mechanism for the improvement, we investigate the energetics of the junction by measuring the relative alignment of the band edges, using Kelvin probe and cyclic voltammetry. Measuring the external quantum efficiency and absorption we find that the improvement is not mainly from electronic improvements but from enhanced absorption of the CQD absorber. We demonstrate experimentally and theoretically, by employing a transfer-matrix model, that the transparent PMMA matrix acts as an optical spacer, which leads to an enhanced absorption in the absorber layer. Lastly, with these electronic and optical enhancements, the efficiency of the PbS CQD solar cells improved from 4.0% to 6.0%.},
doi = {10.1021/acsphotonics.8b00982},
journal = {ACS Photonics},
issn = {2330-4022},
number = 12,
volume = 5,
place = {United States},
year = {2018},
month = {11}
}

Journal Article:
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