Enhanced photoconductivity of C60 doped poly(3-alkylthiophene)

Yoshino, Katsumi; Yin, Xi; Morita, Shigenori; Kawai, Tsuyoshi; Zakhidov, Anvar

doi:10.1016/0038-1098(93)90352-n

Cited by 165 publications

(76 citation statements)

References 20 publications

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“…The signal intensity under the dark condition was negligibly small. For comparison, the absorption spectrum of the RR-P3OT/ C 60 composite (C 60 : 5 mol%) (solid line) and photocurrent spectrum of a composite of regiorandom poly(3-octadecylthiophene) (RRa-P3ODT) and C 60 (C 60 : 5 mol%) (dotted line) [17] are shown together in Fig. 2.…”

Section: Resultsmentioning

confidence: 99%

“…Composites of conjugated polymer, such as poly(3-alkylthiophene) (PAT) or PPV derivatives, and a high electron-affinity species of fullerene (C 60 ) show highly efficient photoinduced electron transfer between the polymer and C 60 ; then positive polarons on the polymer chain and C À1 60 radical anions are formed, respectively. These composites have been extensively studied by various methods such as optical spectroscopy [13][14][15], photoconductivity [16][17][18], light-induced ESR (LESR) [14,15,19], optically detected magnetic resonance [20,21], etc. We have also recently observed a remarkable enhancement of the LESR signals of the regioregular PAT/C 60 composites in the excitation spectrum at around 1.8 eV [22], which is consistent with the enhancement of the photoconductivity at around 1.8 eV where optically forbidden transition of C 60 monomer exists [16,17].…”

Section: Introductionmentioning

confidence: 99%

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Nanoscale spatial extent of photogenerated polarons in regioregular poly(3-octylthiophene)

Marumoto

Takeuchi

Kuroda

2003

Chemical Physics Letters

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nanoscale spatial extent of photogenerated polarons in regioregular poly(3-octylthiophene)

Marumoto

Takeuchi

Kuroda

2003

Chemical Physics Letters

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“…811 Recently, fullerene derivatives have been widely applied to construct photovoltaic cells. 12,13 For further advances of these chemically modified fullerenes as molecular electronic devices, it is very important to reveal the general roles of the bridges in the covalently connected donor bridgeacceptor (DBA) systems, in which the donor and acceptor can be photo-excited as illustrated in Figure 1. 14 When the D moiety in a DBA system is photo-excited, the excited state of D (D*) acts as a photosensitizing electron donor, thus CS takes place from D* to the A moiety through the LUMO of B, giving finally the radical ion pair D•+ …”

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confidence: 99%

Roles of Molecular Wires between Fullerenes and Electron Donors in Photoinduced Electron Transfer

Ito

Yamanaka

2009

Bulletin of the Chemical Society of Japan

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In the photoinduced intramolecular electron transfer events of donorbridgeacceptor molecular systems, the bridges play important roles. In the first part of this account, we review charge separation and charge recombination of porphyrinbridgefullerene systems, in which the porphyrin acts as a photosensitizing electron donor, whereas the ground state of the C 60 moiety acts as an electron acceptor. In such systems, the charge separation usually takes place through the LUMO of the bridges via a super-exchange mechanism and/or a hopping mechanism, depending on their relative LUMO energy levels. On the other hand, the charge recombination of the radical ion pairs usually takes place through the HOMO of the bridges. In the second part, research of charge separation via the excited state of fullerene through the HOMO of the bridges is reviewed. So far, very small damping factors have been reported for ³-conjugated bridges such as oligophenyleneacetylenes, oligothiophenes, and oligothiophenevinylenes. On summarizing these results, it is revealed that switching from the super-exchange mechanism in short bridges to hopping mechanism in longer bridges is important to achieve long distance electron transfer through the bridges.Photoinduced electron transfer (ET) of donoracceptor systems is the most elementary of all photochemical reactions, and plays a crucial role in many essential photoactive devices.14 The functions of conjugated nano-scale donor acceptor molecules are useful for molecular electronic devices 5 and photovoltaic cells. 6,7 Photo-induced electron-transfer systems exhibiting charge-separation (CS) and charge-recombination (CR) processes of the covalently connected donorspacer acceptor systems, in which the spacers are flexible methylene chains, have been extensively studied by the Okada, Mataga, Sakata, and Misumi groups. 811 Recently, fullerene derivatives have been widely applied to construct photovoltaic cells. 12,13 For further advances of these chemically modified fullerenes as molecular electronic devices, it is very important to reveal the general roles of the bridges in the covalently connected donor bridgeacceptor (DBA) systems, in which the donor and acceptor can be photo-excited as illustrated in Figure 1. 14 When the D moiety in a DBA system is photo-excited, the excited state of D (D*) acts as a photosensitizing electron donor, thus CS takes place from D* to the A moiety through the LUMO of B, giving finally the radical ion pair D•+ BA•¹ as illustrated in Figure 2. In this photosensitizing CS process via D*, two cases can be considered depending on the energy level of the LUMO of the B unit relative to the LUMO level of D. One is super-exchange, in which the LUMO energy level of B is higher than the LUMO levels of D and A and another is electron hopping, in which the LUMO level of B is lower than the LUMO level of D. 15,16 Thus, in the superexchange mechanism, the first-step CS (CS-1) after initial photo-excitation (CS-0) is endothermic and the second-step CS (CS-2) is exothermic as shown in F...

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“…The idea of using this property in conjunction with a molecular electron acceptor to achieve long-living charge separation was based on the stability of the photoinduced non-linear excitations (such as polaron) on the conjugated polymer backbone. Independently, the Santa Barbara-and Osaka group reported studies on the photophysics of mixtures and bilayers of conjugated polymers with fullerenes [5,6,[15][16][17][18][19][20][21][22][23]. The experiments clearly gave evidence of an ultrafast (subpicosecond), reversible, metastable photoinduced electron transfer from conjugated polymers onto the C 60 in solid films (see Fig.…”

Section: Conjugated Polymers As Photoexcited Donorsmentioning

confidence: 99%

“…21 shows the dependence of the short circuit current and the photocurrent at -1 V (reverse) bias as a function of the illumination intensity (514.5 nm); the data show no indication of saturation at light intensities up to ca. 1 W/cm 2 .…”

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confidence: 99%

Conjugated Polymer‐Based Plastic Solar Cells

Brabec

Sariçiftçi

1999

Semiconducting Polymers

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A tremendous research effort was devoted to the development of photovoltaic cells during the late seventies and early eighties. During this time interest was also devoted to the development of organic semiconductors, because they offer the advantages of low cost and facile processing. Organic materials for use in photovoltaic devices require a good chemical stability and large optical absorption in the visible range. For this purpose the first studied compounds were merocyanines [1] and phthalocyanines [2], which can readily be deposited as a thin film on various even flexible substrates by vacuum evaporation. Power conversion efficiencies of such devices are about 1% for small size photovoltaic elements.It is indeed intriguing and economically advantageous to think of large area photovoltaic elements based on thin plastic films, cut from rolls and deployed on permanent structures and surfaces. In order to fulfil these low cost and large area requirements, cheap production technologies for large scale coating must be used together with low cost material. Polymer photovoltaic cells hold the potential for such low cost cells. The flexibility of chemical tailoring of desired properties, as well as the cheap technology already well developed for all kinds of plastic thin film applications, meet exactly the above mentioned demands for cheap photovoltaic device production. The mechanical flexibility of plastic materials is useful for all photovoltaic applications onto curved surfaces for indoor as well as outdoor applications.Efficiencies of the first polymeric solar cells, based on hole conducting conjugated polymers (mainly polyacetylene) were rather discouraging [3]. However, the breakthrough to higher efficiencies was achieved by switching to different classes of electron-donor type-conjugated polymers (polythiophenes (PT), poly(para-phenylene vinylene)s (PPV) and their derivatives) and by mixing them with suitable electron acceptors [4]. Prototypes of photovoltaic devices based on a polymeric donor/acceptor networks showed solar energy conversion efficiencies of around 1% [5]. In particular, the photovoltaic properties and the photophysics of conjugated polymer/fullerene solid composites have been well investigated over the last few years [6].Besides the necessity for improvement in efficiency, stability is another problem for all the applications of conjugated polymers. First experiences on conjuSemiconducting Polymers: Chemistry, Physics and Engineering. Edited by G. Hadziioannou and P. F. van Hutten

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Enhanced photoconductivity of C60 doped poly(3-alkylthiophene)

Cited by 165 publications

References 20 publications

Nanoscale spatial extent of photogenerated polarons in regioregular poly(3-octylthiophene)

Nanoscale spatial extent of photogenerated polarons in regioregular poly(3-octylthiophene)

Roles of Molecular Wires between Fullerenes and Electron Donors in Photoinduced Electron Transfer

Conjugated Polymer‐Based Plastic Solar Cells

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