Side chain effect on electronic structure of spin-coated films of [6,6]-phenyl-C61-butyric acid methyl ester and its bis-adduct

Akaike, Kouki; Kanai, Kaname; Ouchi, Yukio; Seki, Kazuhiko

doi:10.1016/j.chemphys.2013.02.011

Cited by 11 publications

(5 citation statements)

References 20 publications

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“…Similarly, EAs of 3.9, 24 3.7, 27 and 3.80 eV 26 for PC 61 BM, 3.7 eV for PC 71 BM, 28 3.4 eV for bis-PCBM, 27 and 3.57 eV for ICBA 29 are in a good agreement with the values determined by the present work within the experimental uncertainties. Although C 60 and C 70 may be durable, the fullerene derivatives with alkyl chains are expected to be more sensitive to electron bombardment, 30 and the values determined using the conventional IPES may be questionable in view of the sample damage.…”

Section: Resultssupporting

confidence: 90%

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Low-Energy Inverse Photoemission Study on the Electron Affinities of Fullerene Derivatives for Organic Photovoltaic Cells

Yoshida

2014

J. Phys. Chem. C

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The lowest unoccupied molecular orbital (LUMO) levels of six fullerene derivatives frequently used for organic photovoltaic cells are examined in the solid state. We employed a new experimental technique, low-energy inverse photoemission spectroscopy (LEIPS), which allows us to determine the electron affinities of solid samples within the uncertainties of 0.1 eV. Using the precisely determined electron affinities, the energy difference between the ionization energy of donor and the electron affinity of acceptor is compared with the open circuit voltage for various polymer/fullerene combinations taken from the literature. The result suggests that the well-known relation between the energy difference and the open circuit voltage should be reconsidered.

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Section: Resultssupporting

confidence: 90%

“…The ionization energies I of the fullerene and its derivatives taken from the literature ,− ,− are listed in Table . The bandgap (transport gap) E g is evaluated as the difference between the ionization energy I and electron affinity A in the solid state as shown in Table .…”

Section: Resultsmentioning

confidence: 99%

Low-Energy Inverse Photoemission Study on the Electron Affinities of Fullerene Derivatives for Organic Photovoltaic Cells

Yoshida

2014

J. Phys. Chem. C

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“…In addition, the open-circuit voltage ( V oc ) of the photodiodes increases from 0.09 V in the P3HT:PCBM:PS device to 0.43 and 0.47 V in the P3HT:PCBM and P3HT:PCBM:SIS ones, respectively. The LUMO of PCBM is located at 3.7 eV . It has been reported that V oc of an organic photodiode is proportional to the energy difference between the LUMO of the acceptor and the HOMO of the donor, which is consistent with our measurements, as shown in Figure c.…”

Section: Discussionsupporting

confidence: 92%

“…The LUMO of PCBM is located at 3.7 eV. 54 It has been reported that V oc of an organic photodiode is proportional to the energy difference between the LUMO of the acceptor and the HOMO of the donor, 55 which is consistent with our measurements, as shown in Figure 3c. A summary of V oc and short-circuit current (I sc ) of a total of seven devices fabricated in the same batch is shown in Figure S15 for photodiodes with the P3HT:PCBM:PS (1:1:5), P3HT:PCBM (1:1), and P3HT:PCBM:SIS (1:1:5) light absorbers, respectively.…”

Section: ■ Discussionsupporting

confidence: 92%

Stretchable Photodiodes with Polymer-Engineered Semiconductor Nanowires for Wearable Photoplethysmography

Mao

Shan

et al. 2023

ACS Appl. Mater. Interfaces

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Healthcare systems worldwide have been stressed to provide sufficient resources to serve the increasing and aging population in our society. The situation became more challenging at the time of pandemic. Technology advancement, especially the adoption of wearable health monitoring devices, has provided an important supplement to current clinical equipment. Most health monitoring devices are rigid, however, human tissues are soft. Such a difference has prohibited intimate contact between the two and jeopardized wearing comfortableness, which hurdles measurement accuracy especially during longtime usage. Here, we report a soft and stretchable photodiode that can conformally adhere onto the human body without any pressure and measure cardiovascular variables for an extended period with higher reliability than commercial devices. The photodiode used a composite light absorber consisting of an organic bulk heterojunction embedded into an elastic polymer matrix. It is discovered that the elastic polymer matrix not only improves the morphology of the bulk heterojunction for obtaining the desired mechanical properties but also alters its electronic band structure and improves the electrical properties that lead to a reduced dark current and enhanced photovoltage in the stretchable photodiode. The work has demonstrated high fidelity measurements and longtime monitoring of heat rate variability and oxygen saturation, potentially enabling next-generation wearable photoplethysmography devices for point-of-care diagnosis of cardiovascular diseases in a more accessible and affordable way.

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“…The effects of the orientational change on the photovoltaic properties of state-of-the-art organic semiconductors appear to be complex. The semiconductors typically have various side chains to ensure solubility, carrier transport, and photoabsorption − , and to control the energies of the highest-occupied molecular orbital (HOMO) and lowest-unoccupied molecular orbital (LUMO). − In principle, the interface in a bulk heterojunction can be formed by direct contact of the π-conjugated backbone or by indirect contact through the side chains. In the indirect case, the physical distance between the hole at the donor and the electron at the acceptor is larger, which reduces the Coulomb interaction binding the charge pairs in the charge-transfer (CT) states.…”

Section: Introductionmentioning

confidence: 99%

Effects of Molecular Orientation of a Fullerene Derivative at the Donor/Acceptor Interface on the Device Performance of Organic Photovoltaics

et al. 2018

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Designing donor/acceptor (D/A) interfaces that can efficiently generate free carriers is an attractive research target for organic photovoltaics (OPVs). While many reports suggest that the molecular orientation of the donor at the D/A interface influences the free-charge generation and recombination, the effects of the acceptor orientation on these processes remain elusive. In this work, we demonstrate that [6,6]-phenyl-C 61 -butyric acid methyl ester (PC 61 BM) changes its molecular orientation at the film surface on crystallization, resulting in the preferential surface exposure of the side chains. Photoelectron spectra of amorphous-and crystalline-PC 61 BM/sexithiophene (6T) interfaces and analysis of the external quantum efficiency and electroluminescence of bilayer OPVs in the charge-transfer absorption range reveal that the orientational change of PC 61 BM raises the energy of the charge-transfer state at the D/A interface. In addition, the PC 61 BM side chain at the crystalline-PC 61 BM/6T interface reduces the electronic coupling between the charge-transfer and ground states, suppressing carrier recombination without sacrificing photocurrent. These two factors lead to the higher open-circuit voltage of crystalline-PC 61 BM/6T OPV compared with its amorphous counterpart. This work directly links the interface and photovoltaic properties, highlighting the role of the acceptor's orientation in determining the efficiency of OPVs.

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Side chain effect on electronic structure of spin-coated films of [6,6]-phenyl-C61-butyric acid methyl ester and its bis-adduct

Cited by 11 publications

References 20 publications

Low-Energy Inverse Photoemission Study on the Electron Affinities of Fullerene Derivatives for Organic Photovoltaic Cells

Low-Energy Inverse Photoemission Study on the Electron Affinities of Fullerene Derivatives for Organic Photovoltaic Cells

Stretchable Photodiodes with Polymer-Engineered Semiconductor Nanowires for Wearable Photoplethysmography

Effects of Molecular Orientation of a Fullerene Derivative at the Donor/Acceptor Interface on the Device Performance of Organic Photovoltaics

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