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Kazuya Tada - One of the best experts on this subject based on the ideXlab platform.

  • validation of opposed two diode equivalent circuit model for s shaped characteristic in polymer Photocell by low light characterization
    Organic Electronics, 2017
    Co-Authors: Kazuya Tada
    Abstract:

    Abstract The opposed two-diode equivalent-circuit model consisting of a traditional one-diode Photocell model and a parasitic diode with a parallel resistance is known to somehow reproduce the S-shaped current-voltage curve of poor organic Photocells. Here, the light-intensity dependencies of the parameters in the model are experimentally studied. On the assumption that the parasitic part is light-insensitive, the parameters of the main part, which are extracted by fitting the current-voltage curves under various illumination intensities with the model, are found to change as those of healthy Photocells do. The reasonable separation of light-sensitive main and light-insensitive parasitic parts validates the model.

  • characteristics of ptb7 c 70 bulk heterojunction Photocell prepared with halogen free solvent at low light illumination
    Polymer Bulletin, 2016
    Co-Authors: Kazuya Tada
    Abstract:

    Increasing social demands for clean and cheap renewable energy sources have been promoting the researches on polymer Photocells based on bulk heterojunction composites consisting of conjugated polymers and fullerenes. The replacement of traditional chloroaromatic solvents such as chlorobenzene with a halogen-free solvent 1,2,4-trimethylbenzene (TMB), which enables the preparation of bulk heterojunction composites with unmodified fullerenes, potentially reduces the economic and environmental costs of organic bulk heterojunction Photocells. In this study, photovoltaic characteristics of PTB7:C70 bulk heterojunction Photocells prepared with TMB at low light intensity are studied. It has been found that the power conversion efficiency (PCE) of a Photocell with ITO/PEDOT:PSS/PTB7:C70/Al structure whose PCE is approximately 3 % under AM1.5G 1 sun (100 mW/cm−2) illumination increases with decreased illumination light intensity, being 5.9 % at 10−3 sun illumination. An analysis of current–voltage characteristics suggests that the increased PCE is mainly due to increased shunt resistance and decreased saturation current of the diode in the model. The results indicate that the solution-processed organic Photocell based on unmodified fullerene prepared with halogen-free solvent is a promising candidate for environmental-friendly device for indoor light harvesting.

  • characterization of polymer bulk heterojunction Photocell with unmodified c70 prepared with halogen free solvent for indoor light harvesting
    Organic Electronics, 2016
    Co-Authors: Kazuya Tada
    Abstract:

    Abstract Although Photocells are commonly characterized under AM1.5G 100 mW cm−2 (1 sun) illumination, their performance under low light illumination is also important, because Photocells are frequently used for indoor applications. In this study, polymer Photocells based on a bulk heterojunction composite consisting of a low energy gap polymer PTB7 and unmodified C70 prepared with a halogen-free solvent 1,2,4-trimethylbenzene have been characterized under the illumination of 1 sun or below. A typical Photocell with the power conversion efficiency (PCE) of 4% at 1 sun shows the PCE of approximately 7% at 10−3 sun, which seems to fit for some indoor applications such as a permanent power source for a wireless sensor node. The sublinear dependence of short-circuit photocurrent on light intensity as well as the increase of fill-factor under low light illumination yields the increased efficiency under low light illumination. An analysis employing a one-diode equivalent circuit model suggests that the increased parallel resistance as well as the decreased saturation current of the diode under low light illumination accounts for the latter feature. It is also pointed out that the parallel resistance and/or the saturation current under dark strongly influence the PCE of a Photocell under low light illumination. In addition, the dependence of the device performance on the light intensity is found to be useful for analyzing the effects of the thermal treatment and the PFN interlayer at cathode.

  • parameter extraction from s shaped current voltage characteristics in organic Photocell with opposed two diode model effects of ideality factors and series resistance
    Physica Status Solidi (a), 2015
    Co-Authors: Kazuya Tada
    Abstract:

    Non-traditional Photocells such as organic Photocells frequently show S-shaped current–voltage characteristics, which can be reproduced with not the simple one-diode equivalent-circuit model but an opposed two-diode model. In this study, a facile method for the extraction of the device parameters from S-shaped characteristics of a Photocell using the opposed two-diode model is demonstrated. It was found that the fitting accuracy is insensitive to the ideality factors of the diodes. Moreover, contrary to the preceding studies, the exclusion of the series resistance was found to have a noticeable impact on the fitting results.

  • Thermally robust bulk heterojunction Photocells based on PTB7:C70 composites
    Solar Energy Materials and Solar Cells, 2014
    Co-Authors: Kazuya Tada
    Abstract:

    Abstract Bulk heterojunction (BHJ) Photocells using low energy-gap polymers such as poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) and modified fullerenes such as [6,6]-phenyl-C 71 -butyric acid methyl ester (C 70 -PCBM) show relatively high power conversion efficiency. It is known that the thermal annealing, which effectively improves the photovoltaic performance of BHJ Photocells with semi-crystalline polymers such as poly (3-hexylthiophene), is not applicable to BHJ Photocells with amorphous-type polymers such as PTB7. In this study, it is found that PTB7:C 70 -PCBM BHJ Photocells degrade shortly at 80 °C, which is within the range of the temperature shock cycling test condition specified in IEC 61646, the international standard for testing thin-film photovoltaic module. On the other hand, the photovoltaic performance of PTB7:C 70 BHJ Photocells composite has been found to significantly improve after the thermal annealing at 160 °C. The results strikingly indicate not only that the lack of thermal robustness in PTB7:C 70 -PCBM BHJ Photocells does not mainly arise from the nature of the polymer but the substituents of the fullerene used, but also that neat fullerenes should not be considered as just cheap and nasty substitutes of fullerene derivatives.

Mitsuyoshi Onoda - One of the best experts on this subject based on the ideXlab platform.

  • Poor man's green bulk heterojunction Photocells: A chlorine-free solvent for poly(3-hexylthiophene)/C60composites
    Solar Energy Materials and Solar Cells, 2012
    Co-Authors: Kazuya Tada, Mitsuyoshi Onoda
    Abstract:

    Although C60is unquestionably not only the cheapest but also the most energy-saving fullerene, lack of suitable solvent to make bulk heterojunction composites with it has prevented its use in Photocells. Here, it is shown that a not-so-common organic solvent 1,2,4-trimethylbenzene (TMB) is useful to prepare cost-effective bulk heterojunction composites based on C60. Additionally, chlorine-free TMB is expected to be environmental friendly compared with chloroaromatic solvents commonly used for the preparation of polymer/fullerene composites. A preliminary evaluation indicated that a poly(3-hexylthiophene) (P3HT)/C60bulk heterojunction Photocell prepared from TMB solution shows power conversion efficiency comparable to that of a P3HT/PCBM Photocell, suggesting that C60should be revisited as a promising candidate for an acceptor material in polymer bulk heterojunction composites for low-cost green Photocells. © 2012 Elsevier B.V. All rights reserved.

  • characteristics of poly p pyridyl vinylene poly 3 alkylthiophene heterojunction Photocell
    Japanese Journal of Applied Physics, 1997
    Co-Authors: Kazuya Tada, Mitsuyoshi Onoda, Anvar A. Zakhidov, Katsumi Yoshino
    Abstract:

    Photoirradiation effects of a poly( p-pyridyl vinylene) (PPyV)/poly(3-hexylthiophene) (PAT6) heterojunction Photocell have been investigated. The photovoltaic characteristics of the heterojunction Photocell are considerably improved from those in a single-PAT6-layer Photocell. Quenching of photoluminescence both in the PAT6 layer and in the PPyV layer has also been observed in the PPyV/PAT6 double layer. The observed photoirradiation effects of the heterojunction have been discussed in terms of interfacial photoinduced charge transfer between PAT6 and PPyV.

Mohammad B. Kassim - One of the best experts on this subject based on the ideXlab platform.

  • An overview of Photocells and photoreactors for photoelectrochemical water splitting
    International Journal of Hydrogen Energy, 2010
    Co-Authors: Lorna Jeffery Minggu, Wan Ramli Wan Daud, Mohammad B. Kassim
    Abstract:

    Solar hydrogen production from direct photoelectrochemical (PEC) water splitting is the ultimate goal for a sustainable, renewable and clean hydrogen economy. While there are numerous studies on solving the two main photoelectrode (PE) material issues i.e. efficiency and stability, there is no standard Photocell or photoreactor used in the study. The main requirement for the Photocell or photoreactor is to allow maximum light to reach the PE. This paper presents an overview of the PE configurations and the possible Photocell and photoreactor design for hydrogen production by PEC water splitting.

  • An overview of Photocells and photoreactors for photoelectrochemical water splitting
    International Journal of Hydrogen Energy, 2010
    Co-Authors: Lorna Jeffery Minggu, Wan Ramli Wan Daud, Mohammad B. Kassim
    Abstract:

    Solar hydrogen production from direct photoelectrochemical (PEC) water splitting is the ultimate goal for a sustainable, renewable and clean hydrogen economy. While there are numerous studies on solving the two main photoelectrode (PE) material issues i.e. efficiency and stability, there is no standard Photocell or photoreactor used in the study. The main requirement for the Photocell or photoreactor is to allow maximum light to reach the PE. This paper presents an overview of the PE configurations and the possible Photocell and photoreactor design for hydrogen production by PEC water splitting. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

Katsumi Yoshino - One of the best experts on this subject based on the ideXlab platform.

  • characteristics of poly p pyridyl vinylene poly 3 alkylthiophene heterojunction Photocell
    Japanese Journal of Applied Physics, 1997
    Co-Authors: Kazuya Tada, Mitsuyoshi Onoda, Anvar A. Zakhidov, Katsumi Yoshino
    Abstract:

    Photoirradiation effects of a poly( p-pyridyl vinylene) (PPyV)/poly(3-hexylthiophene) (PAT6) heterojunction Photocell have been investigated. The photovoltaic characteristics of the heterojunction Photocell are considerably improved from those in a single-PAT6-layer Photocell. Quenching of photoluminescence both in the PAT6 layer and in the PPyV layer has also been observed in the PPyV/PAT6 double layer. The observed photoirradiation effects of the heterojunction have been discussed in terms of interfacial photoinduced charge transfer between PAT6 and PPyV.

  • Conducting polymer color sensor
    Japanese Journal of Applied Physics Part 2: Letters, 1997
    Co-Authors: Kentaro Tada, Katsumi Yoshino
    Abstract:

    A color sensor device using conducting polymer poly(3-hexylthiophene) (PAT6), has been fabricated and characterized. The device consists of two Photocells made of the same conducting polymer with different polymer thicknesses, and which exploits the difference in the photocurrent spectrum of the Photocells. The color of the irradiated light can be detected by measuring the ratio of the short-circuit photocurrent of two Photocells with different PAT6 thicknesses. The color sensor proposed here is suitable for large-area sensor systems such as the integrated image sensor device because of its simple structure. [on SciFinder (R)]

  • Spectral Characteristics of C60-Conducting Polymer Junctions: Various Molecular D-A Type Photocells
    Molecular Crystals and Liquid Crystals, 1994
    Co-Authors: Seizo Morita, A. A. Zakhidov, Katsumi Yoshino
    Abstract:

    Abstract We have found recently that thin film layered heterojunction between C60 and conducting polymer, like poly(3-alkylthiophene) (PAT) shows a photovoltaic effect due to photoinduced charge transfer at the interface. Here we describe two other examples of such Photocells in RO-PPV/C60 and PPP/C60 heterojunctions and study their spectral characteristics. Contrary to conventional inorganic semiconductor p-n junction Photocells, the C60-PAT junction can be rather viewed as molecular donor-acceptor (D-A) type Photocell in which the processes of photogeneration and separation of charge carriers are quite distinct. In a p-n junction free electron-hole pairs are known to be primarily photogenerated at interband transition and then separated in the internal electric field of the barrier, while in D-A molecular Photocell mainly neutral excitons are first created by light, with charges being primarily separated at the narrow interface region due to D-A type intermolecular charge transfer interactions. We analy...

Lightmart - One of the best experts on this subject based on the ideXlab platform.