Theoretical rationalization for reduced charge recombination in bulky carbazole-based sensitizers in solar cells

© 2017 Wiley Periodicals, Inc. The search for greater efficiency in organic dye-sensitized solar cells (DSCs) and in their perovskite cousins is greatly aided by a more complete understanding of the spectral and morphological properties of the photoactive layer. This investigation resolves a discrep...

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Main Authors: Surakhot Y., Laszlo V., Chitpakdee C., Promarak V., Sudyoadsuk T., Kungwan N., Kowalczyk T., Irle S., Jungsuttiwong S.
Format: Journal
Published: 2017
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http://cmuir.cmu.ac.th/jspui/handle/6653943832/40466
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spelling th-cmuir.6653943832-404662017-09-28T04:09:42Z Theoretical rationalization for reduced charge recombination in bulky carbazole-based sensitizers in solar cells Surakhot Y. Laszlo V. Chitpakdee C. Promarak V. Sudyoadsuk T. Kungwan N. Kowalczyk T. Irle S. Jungsuttiwong S. © 2017 Wiley Periodicals, Inc. The search for greater efficiency in organic dye-sensitized solar cells (DSCs) and in their perovskite cousins is greatly aided by a more complete understanding of the spectral and morphological properties of the photoactive layer. This investigation resolves a discrepancy in the observed photoconversion efficiency (PCE) of two closely related DSCs based on carbazole-containing D–π–A organic sensitizers. Detailed theoretical characterization of the absorption spectra, dye adsorption on TiO 2 , and electronic couplings for charge separation and recombination permit a systematic determination of the origin of the difference in PCE. Although the two dyes produce similar spectral features, ground- and excited-state density functional theory (DFT) simulations reveal that the dye with the bulkier donor group adsorbs more strongly to TiO 2 , experiences limited π–π aggregation, and is more resistant to loss of excitation energy via charge recombination on the dye. The effects of conformational flexibility on absorption spectra and on the electronic coupling between the bright exciton and charge-transfer states are revealed to be substantial and are characterized through density-functional tight-binding (DFTB) molecular dynamics sampling. These simulations offer a mechanistic explanation for the superior open-circuit voltage and short-circuit current of the bulky-donor dye sensitizer and provide theoretical justification of an important design feature for the pursuit of greater photocurrent efficiency in DSCs. © 2017 Wiley Periodicals, Inc. 2017-09-28T04:09:42Z 2017-09-28T04:09:42Z 12 Journal 01928651 2-s2.0-85013031181 10.1002/jcc.24751 https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85013031181&origin=inward http://cmuir.cmu.ac.th/jspui/handle/6653943832/40466
institution Chiang Mai University
building Chiang Mai University Library
country Thailand
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description © 2017 Wiley Periodicals, Inc. The search for greater efficiency in organic dye-sensitized solar cells (DSCs) and in their perovskite cousins is greatly aided by a more complete understanding of the spectral and morphological properties of the photoactive layer. This investigation resolves a discrepancy in the observed photoconversion efficiency (PCE) of two closely related DSCs based on carbazole-containing D–π–A organic sensitizers. Detailed theoretical characterization of the absorption spectra, dye adsorption on TiO 2 , and electronic couplings for charge separation and recombination permit a systematic determination of the origin of the difference in PCE. Although the two dyes produce similar spectral features, ground- and excited-state density functional theory (DFT) simulations reveal that the dye with the bulkier donor group adsorbs more strongly to TiO 2 , experiences limited π–π aggregation, and is more resistant to loss of excitation energy via charge recombination on the dye. The effects of conformational flexibility on absorption spectra and on the electronic coupling between the bright exciton and charge-transfer states are revealed to be substantial and are characterized through density-functional tight-binding (DFTB) molecular dynamics sampling. These simulations offer a mechanistic explanation for the superior open-circuit voltage and short-circuit current of the bulky-donor dye sensitizer and provide theoretical justification of an important design feature for the pursuit of greater photocurrent efficiency in DSCs. © 2017 Wiley Periodicals, Inc.
format Journal
author Surakhot Y.
Laszlo V.
Chitpakdee C.
Promarak V.
Sudyoadsuk T.
Kungwan N.
Kowalczyk T.
Irle S.
Jungsuttiwong S.
spellingShingle Surakhot Y.
Laszlo V.
Chitpakdee C.
Promarak V.
Sudyoadsuk T.
Kungwan N.
Kowalczyk T.
Irle S.
Jungsuttiwong S.
Theoretical rationalization for reduced charge recombination in bulky carbazole-based sensitizers in solar cells
author_facet Surakhot Y.
Laszlo V.
Chitpakdee C.
Promarak V.
Sudyoadsuk T.
Kungwan N.
Kowalczyk T.
Irle S.
Jungsuttiwong S.
author_sort Surakhot Y.
title Theoretical rationalization for reduced charge recombination in bulky carbazole-based sensitizers in solar cells
title_short Theoretical rationalization for reduced charge recombination in bulky carbazole-based sensitizers in solar cells
title_full Theoretical rationalization for reduced charge recombination in bulky carbazole-based sensitizers in solar cells
title_fullStr Theoretical rationalization for reduced charge recombination in bulky carbazole-based sensitizers in solar cells
title_full_unstemmed Theoretical rationalization for reduced charge recombination in bulky carbazole-based sensitizers in solar cells
title_sort theoretical rationalization for reduced charge recombination in bulky carbazole-based sensitizers in solar cells
publishDate 2017
url https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85013031181&origin=inward
http://cmuir.cmu.ac.th/jspui/handle/6653943832/40466
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