Organic photoconductors with C60 for xerography

Schlebusch, C.; Morenzin, J.; Keßler, Barbara; Eberhardt, W.

doi:10.1016/s0008-6223(98)00260-7

Cited by 11 publications

(11 citation statements)

References 7 publications

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“…This spatial separation prevents direct electron-hole recombination. Studies by photoelectron spectroscopy (PES) have shown that the charge transfer process is energetically possible, both in layered systems [4,5] as well as in heterogeneous mixtures [10]. Here, we concentrate on the material combination of the organic photoreceptor copper phthalocyanine (CuPC), which is a ubiquitous component of photochemical and light harvesting applications [1][2][3], with C 60 molecules as electron acceptors.A recent report on CuPC-C 60 interfaces indicates that, when CuPC is deposited atop of a C 60 film, the sample surface tends to charge up, unlike the case of a C 60 film grown on top of a CuPC covered substrate [7].…”

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“…Consequently, many research efforts focus on the identification of methods to quench the recombination process. Empirically, the admixture of C 60 into organic photoreceptor films has led to significant progress in this respect [1][2][3][4][5][6][7][8]. Based on observations of intrinsic fluorescence quenching [1,2] as well as from photoemission studies of the band alignment in thin film systems [9], it has been concluded that after the initial electron-hole production in the chromophore, the electron is captured by the C 60 molecule, thus spatially separating the electron from the hole in the chromophore molecule.…”

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Site-specific probing of charge transfer dynamics in organic photovoltaics

Arion

Neppl

Roth

et al. 2015

Applied Physics Letters

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We report the site-specific probing of charge-transfer dynamics in a prototype system for organic photovoltaics (OPV) by picosecond time-resolved X-ray photoelectron spectroscopy. A layered system consisting of approximately two monolayers of C60 deposited on top of a thin film of CopperPhthalocyanine (CuPC) is excited by an optical pump pulse and the induced electronic dynamics are probed with 590 eV X-ray pulses. Charge transfer from the electron donor (CuPC) to the acceptor (C60) and subsequent charge carrier dynamics are monitored by recording the time-dependent C 1s core level photoemission spectrum of the system. The arrival of electrons in the C60 layer is readily observed as a completely reversible, transient shift of the C60 associated C 1s core level, while the C 1s level of the CuPC remains unchanged. The capability to probe charge transfer and recombination dynamics in OPV assemblies directly in the time domain and from the perspective of well-defined domains is expected to open additional pathways to better understand and optimize the performance of this emerging technology.PACS numbers: 88.40.jr,79.60.-i,78.47.da, 78.20.-e Research on materials for organic photovoltaic (OPV) applications is driven mostly by two figures of merit: the light-to-current conversion efficiency and the cost of production, which would make the technology suitable for widespread implementation. So far, OPVs meet the second criterion, as they can easily be prepared by deposition from solutions, or by low-cost printing techniques, rather than using more demanding vacuum deposition methods. However, the relatively low conversion efficiency of OPVs remains a significant challenge. It is generally accepted that recombination of the photo-induced electron-hole pair or excitonic state in the photoreceptive material is one of the major loss mechanisms. Consequently, many research efforts focus on the identification of methods to quench the recombination process. Empirically, the admixture of C 60 into organic photoreceptor films has led to significant progress in this respect [1][2][3][4][5][6][7][8]. Based on observations of intrinsic fluorescence quenching [1, 2] as well as from photoemission studies of the band alignment in thin film systems [9], it has been concluded that after the initial electron-hole production in the chromophore, the electron is captured by the C 60 molecule, thus spatially separating the electron from the hole in the chromophore molecule. This spatial separation prevents direct electron-hole recombination. Studies by photoelectron spectroscopy (PES) have shown that the charge transfer process is energetically possible, both in layered systems [4,5] as well as in heterogeneous mixtures [10]. Here, we concentrate on the material combination of the organic photoreceptor copper phthalocyanine (CuPC), which is a ubiquitous component of photochemical and light harvesting applications [1][2][3], with C 60 molecules as electron acceptors.A recent report on CuPC-C 60 interfaces indicates that, when CuPC is depos...

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Site-specific probing of charge transfer dynamics in organic photovoltaics

Arion

Neppl

Roth

et al. 2015

Applied Physics Letters

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“…4,19,20 Phthalocyanines have been also studied successfully as p-type materials in organic solar cells. 8,9,12 The complementarity of their visible ͑VIS͒ absorption spectra as well as of their electron affinity nature ͑i.e., n-type C 60 and p-type Zn-Pc͒, makes them two natural candidates for developing p -n organic photovoltaic devices.…”

Section: Introductionmentioning

confidence: 99%

Weak intrinsic charge transfer complexes: A new route for developing wide spectrum organic photovoltaic cells

Ruani¹,

Fontanini²,

Murgia³

et al. 2002

The Journal of Chemical Physics

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Solar emission extends in the near IR and one of the main issues in designing organic solar cells resides in extending the response into the near IR. Here we show that this may be achieved by making intimate interpenetrated networks of C 60 and Zn-phthalocyanine ͑Zn-Pc͒ in the solid. Various spectroscopic investigations of co-sublimated thin films of C 60 and Zn-phthalocyanine give indeed ample evidence of the existence of a weak charge transfer ͑CT͒ state at 1.4 eV, which quenches the photoluminescence of both molecules. The films produced by co-sublimation undergo to a spinodal decomposition producing domains prevalently constituted by Zn-Pc in contact with domain prevalently of C 60 . The domains size depends on the deposition conditions ͑rate, stoichiometry, and substrate temperature͒ forming a percolating 3D network. The separation in different domains is confirmed by the observation of two overlapping peaks, in the resonant Raman spectrum, that correspond to the A g (2) pinch mode ͑CvC double bond stretching͒ for pristine C 60 and for a partially (ϳ0.25e Ϫ ) doped one. This indicates that only those donor molecules at the grain boundary, which are in contact with C 60 , give rise to a renormalized new CT ground state. Photocurrent measurements of interpenetrated networks of C 60 and Zn-Pc show a linear dependence with respect to the incident light as a consequence of direct absorption within the CT state. The CT state favors the charge separation between the two components, when it is inserted as interface in the organic photovoltaic p -n junction thus increasing the efficiency of the device.

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“…Phthalocyanines (Pcs) and their derivatives are excellent organic semiconductors and they have potential applications in chemical sensors [1][2][3], xerography [4], photoswitches [5], laser recording materials [6], photovoltaic cell [7,8] and field effect transistors [9,10]. Recently, one-dimensional structures of Pcs attract great interest, because they can offer larger surface areas compared to their films or bulk materials which can cause the enhanced optical and electronic properties.…”

Section: Introductionmentioning

confidence: 99%