Direct Observation of the Charge Transfer States from a Non-Fullerene Organic Solar Cell with a Small Driving Force

Peng Wan; Xingtong Chen; Qi Liu; Sudhi Mahadevan; Mingxuan Guo; Jinjing Qiu; Xiaojuan Sun; Sai-Wing Tsang; Maojie Zhang; Yongfang Li; Song Chen

doi:10.1021/acs.jpclett.1c03365

Direct Observation of the Charge Transfer States from a Non-Fullerene Organic Solar Cell with a Small Driving Force

Peng Wan
, Xingtong Chen
, Qi Liu
, Sudhi Mahadevan
, Mingxuan Guo
, Jinjing Qiu
, Xiaojuan Sun
, Sai-Wing Tsang^*
, Maojie Zhang^*
, Yongfang Li
, Song Chen^*

^*Corresponding author for this work

Department of Materials Science and Engineering

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

40 Citations (Scopus)

89 Downloads (CityUHK Scholars)

Abstract

For organic solar cells (OSCs), the charge generation mechanism and the recombination loss are heavily linked with charge transfer states (CTS). Measuring the energy of CTS (E_CT) by the most widely used technique, however, has become challenging for the non-fullerene-based OSCs with a small driving force, resulting in difficulty in the understanding of OSC physics. Herein, we present a study of the PM6:Y6 bulk heterojunction. It is demonstrated that electro-absorption can not only reveal the dipolar nature of Y6 but also resolve the morphology-dependent absorption signal of CTS in the sub-bandgap region. The device with the optimum blending weight ratio shows an E_CT of 1.27 eV, which is confirmed by independent measurements. Because of the charge transfer characteristics of Y6, the charge generation at PM6:Y6 interfaces occurs efficiently under a small but non-negligible driving force of 0.14 eV, and the total recombination loss is as low as 0.43 eV.

Original language	English
Pages (from-to)	10595-10602
Journal	Journal of Physical Chemistry Letters
Volume	12
Issue number	43
Online published	25 Oct 2021
DOIs	https://doi.org/10.1021/acs.jpclett.1c03365
Publication status	Published - 4 Nov 2021

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 7 Affordable and Clean Energy

Research Keywords

OPEN-CIRCUIT VOLTAGE
BULK
EFFICIENCY
RECOMBINATION
GENERATION
ENERGY

Publisher's Copyright Statement

This full text is made available under CC-BY 4.0. https://creativecommons.org/licenses/by/4.0/

RGC Funding Information

RGC-funded

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10.1021/acs.jpclett.1c03365

86424899.pdfFinal Published version, 2.77 MBLicence: CC BY

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title = "Direct Observation of the Charge Transfer States from a Non-Fullerene Organic Solar Cell with a Small Driving Force",

abstract = "For organic solar cells (OSCs), the charge generation mechanism and the recombination loss are heavily linked with charge transfer states (CTS). Measuring the energy of CTS (ECT) by the most widely used technique, however, has become challenging for the non-fullerene-based OSCs with a small driving force, resulting in difficulty in the understanding of OSC physics. Herein, we present a study of the PM6:Y6 bulk heterojunction. It is demonstrated that electro-absorption can not only reveal the dipolar nature of Y6 but also resolve the morphology-dependent absorption signal of CTS in the sub-bandgap region. The device with the optimum blending weight ratio shows an ECT of 1.27 eV, which is confirmed by independent measurements. Because of the charge transfer characteristics of Y6, the charge generation at PM6:Y6 interfaces occurs efficiently under a small but non-negligible driving force of 0.14 eV, and the total recombination loss is as low as 0.43 eV.",

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language = "English",

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T1 - Direct Observation of the Charge Transfer States from a Non-Fullerene Organic Solar Cell with a Small Driving Force

AU - Wan, Peng

AU - Chen, Xingtong

AU - Liu, Qi

AU - Mahadevan, Sudhi

AU - Guo, Mingxuan

AU - Qiu, Jinjing

AU - Sun, Xiaojuan

AU - Tsang, Sai-Wing

AU - Zhang, Maojie

AU - Li, Yongfang

AU - Chen, Song

PY - 2021/11/4

Y1 - 2021/11/4

N2 - For organic solar cells (OSCs), the charge generation mechanism and the recombination loss are heavily linked with charge transfer states (CTS). Measuring the energy of CTS (ECT) by the most widely used technique, however, has become challenging for the non-fullerene-based OSCs with a small driving force, resulting in difficulty in the understanding of OSC physics. Herein, we present a study of the PM6:Y6 bulk heterojunction. It is demonstrated that electro-absorption can not only reveal the dipolar nature of Y6 but also resolve the morphology-dependent absorption signal of CTS in the sub-bandgap region. The device with the optimum blending weight ratio shows an ECT of 1.27 eV, which is confirmed by independent measurements. Because of the charge transfer characteristics of Y6, the charge generation at PM6:Y6 interfaces occurs efficiently under a small but non-negligible driving force of 0.14 eV, and the total recombination loss is as low as 0.43 eV.

AB - For organic solar cells (OSCs), the charge generation mechanism and the recombination loss are heavily linked with charge transfer states (CTS). Measuring the energy of CTS (ECT) by the most widely used technique, however, has become challenging for the non-fullerene-based OSCs with a small driving force, resulting in difficulty in the understanding of OSC physics. Herein, we present a study of the PM6:Y6 bulk heterojunction. It is demonstrated that electro-absorption can not only reveal the dipolar nature of Y6 but also resolve the morphology-dependent absorption signal of CTS in the sub-bandgap region. The device with the optimum blending weight ratio shows an ECT of 1.27 eV, which is confirmed by independent measurements. Because of the charge transfer characteristics of Y6, the charge generation at PM6:Y6 interfaces occurs efficiently under a small but non-negligible driving force of 0.14 eV, and the total recombination loss is as low as 0.43 eV.

KW - OPEN-CIRCUIT VOLTAGE

KW - BULK

KW - EFFICIENCY

KW - RECOMBINATION

KW - GENERATION

KW - ENERGY

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DO - 10.1021/acs.jpclett.1c03365

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EP - 10602

JO - Journal of Physical Chemistry Letters

JF - Journal of Physical Chemistry Letters

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ER -

Direct Observation of the Charge Transfer States from a Non-Fullerene Organic Solar Cell with a Small Driving Force

Abstract

UN SDGs

Research Keywords

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RGC Funding Information

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GRF: On the Impact of Electron Back Transfer on the Recombination Loss in Organic Photovoltaic Cells

Cite this

Direct Observation of the Charge Transfer States from a Non-Fullerene Organic Solar Cell with a Small Driving Force

Abstract

UN SDGs

Research Keywords

Publisher's Copyright Statement

RGC Funding Information

Access Output

Other Access Options

Permanent Link

Other Files and Links

Fingerprint

Projects

GRF: On the Impact of Electron Back Transfer on the Recombination Loss in Organic Photovoltaic Cells

Cite this