Evidence of Delocalization in Charge-Transfer State Manifold for Donor:Acceptor Organic Photovoltaics

Zhiqiang Guan; Ho Wa Li; Jinfeng Zhang; Yuanhang Cheng; Qingdan Yang; Ming Fai Lo; Tsz Wai Ng; Sai Wing Tsang; Chun Sing Lee

doi:10.1021/acsami.6b06010

Evidence of Delocalization in Charge-Transfer State Manifold for Donor:Acceptor Organic Photovoltaics

Zhiqiang Guan, Ho Wa Li, Jinfeng Zhang, Yuanhang Cheng, Qingdan Yang, Ming Fai Lo, Tsz Wai Ng, Sai Wing Tsang^*, Chun Sing Lee

^*Corresponding author for this work

City University of Hong Kong

Research output: Contribution to journal › Article › peer-review

11 Citations (Scopus)

Abstract

How charge-transfer states (CTSs) assist charge separation of a Coulombically bound exciton in organic photovoltaics has been a hot topic. It is believed that the delocalization feature of a CTS plays a crucial role in the charge separation process. However, the delocalization of the "hot" and the "relaxed" CTSs is still under debate. Here, with a novel frequency dependent charge-modulated electroabsorption spectroscopy (CMEAS) technique, we elucidate clearly that both "hot" and "relaxed" CTSs are loosely bound and delocalized states. This is confirmed by comparing the CMEAS results of CTSs with those of localized polaron states. Our results reveal the role of CTS delocalization on charge separation and indicate that no substantial delocalization gradient exists in CTSs.

Original language	English
Pages (from-to)	21798-21805
Number of pages	8
Journal	ACS applied materials & interfaces
Volume	8
Issue number	33
DOIs	https://doi.org/10.1021/acsami.6b06010
Publication status	Published - 24 Aug 2016
Externally published	Yes

Keywords

charge-modulated electroabsorption spectroscopy
charge-transfer states
delocalization
organic photovoltaics
polaron states

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10.1021/acsami.6b06010

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title = "Evidence of Delocalization in Charge-Transfer State Manifold for Donor:Acceptor Organic Photovoltaics",

abstract = "How charge-transfer states (CTSs) assist charge separation of a Coulombically bound exciton in organic photovoltaics has been a hot topic. It is believed that the delocalization feature of a CTS plays a crucial role in the charge separation process. However, the delocalization of the {"}hot{"} and the {"}relaxed{"} CTSs is still under debate. Here, with a novel frequency dependent charge-modulated electroabsorption spectroscopy (CMEAS) technique, we elucidate clearly that both {"}hot{"} and {"}relaxed{"} CTSs are loosely bound and delocalized states. This is confirmed by comparing the CMEAS results of CTSs with those of localized polaron states. Our results reveal the role of CTS delocalization on charge separation and indicate that no substantial delocalization gradient exists in CTSs.",

keywords = "charge-modulated electroabsorption spectroscopy, charge-transfer states, delocalization, organic photovoltaics, polaron states",

author = "Zhiqiang Guan and Li, {Ho Wa} and Jinfeng Zhang and Yuanhang Cheng and Qingdan Yang and Lo, {Ming Fai} and Ng, {Tsz Wai} and Tsang, {Sai Wing} and Lee, {Chun Sing}",

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AU - Guan, Zhiqiang

AU - Li, Ho Wa

AU - Zhang, Jinfeng

AU - Cheng, Yuanhang

AU - Yang, Qingdan

AU - Lo, Ming Fai

AU - Ng, Tsz Wai

AU - Tsang, Sai Wing

AU - Lee, Chun Sing

PY - 2016/8/24

Y1 - 2016/8/24

N2 - How charge-transfer states (CTSs) assist charge separation of a Coulombically bound exciton in organic photovoltaics has been a hot topic. It is believed that the delocalization feature of a CTS plays a crucial role in the charge separation process. However, the delocalization of the "hot" and the "relaxed" CTSs is still under debate. Here, with a novel frequency dependent charge-modulated electroabsorption spectroscopy (CMEAS) technique, we elucidate clearly that both "hot" and "relaxed" CTSs are loosely bound and delocalized states. This is confirmed by comparing the CMEAS results of CTSs with those of localized polaron states. Our results reveal the role of CTS delocalization on charge separation and indicate that no substantial delocalization gradient exists in CTSs.

AB - How charge-transfer states (CTSs) assist charge separation of a Coulombically bound exciton in organic photovoltaics has been a hot topic. It is believed that the delocalization feature of a CTS plays a crucial role in the charge separation process. However, the delocalization of the "hot" and the "relaxed" CTSs is still under debate. Here, with a novel frequency dependent charge-modulated electroabsorption spectroscopy (CMEAS) technique, we elucidate clearly that both "hot" and "relaxed" CTSs are loosely bound and delocalized states. This is confirmed by comparing the CMEAS results of CTSs with those of localized polaron states. Our results reveal the role of CTS delocalization on charge separation and indicate that no substantial delocalization gradient exists in CTSs.

KW - charge-modulated electroabsorption spectroscopy

KW - charge-transfer states

KW - delocalization

KW - organic photovoltaics

KW - polaron states

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JO - ACS applied materials & interfaces

JF - ACS applied materials & interfaces

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ER -

Evidence of Delocalization in Charge-Transfer State Manifold for Donor:Acceptor Organic Photovoltaics

Abstract

Keywords

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