Electronic Structure and Interface Properties of a Model Molecule for Organic Solar Cells

Hintz, Holger; Peisert, Heiko; Aygül, Umut; Latteyer, Florian; Biswas, Indro; Nagel, Peter; Merz, Michael; Schuppler, S.; Breusov, Dietrich; Allard, Sybille; Scherf, Ullrich; Chassé, Thomas

doi:10.1002/cphc.200900626

Cited by 21 publications

(29 citation statements)

References 36 publications

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“…On the other hand, the T6 HOMO BE shift is an evidence of the organic involvement in the charge transfer process [3,4,17,21] and is a further indication that the increase in the source drain current in the output and transfer curves is completely due to a surface doping of T6 by PDI- respectively [22,28]. The proposed level alignment at the heterojunction is in agreement with other studied organic systems [2,[29][30][31] and confirms results for the PDI-8CN 2 /T6 bilayers (with different thicknesses) achieved by some of the authors of this study, where a substantial charge transfer process was supposed between the two organics [10].…”

supporting

confidence: 87%

Surface doping in T6/PDI-8CN2 heterostructures investigated by transport and photoemission measurements

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Verucchi

Tatti

et al. 2012

Applied Physics Letters

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ABSTRACT.In this paper, we discuss the surface doping in sexithiophene (T6) organic field-effect transistors by N,N'-bis (n-octyl)-dicyanoperylenediimide (PDI-8CN 2 ). We show that an accumulation heterojunction is formed at the interface between the organic semiconductors and that the consequent band bending in T6 caused by PDI-8CN 2 deposition can be addressed as the cause of the surface doping in T6 transistors. Several evidences of this phenomenon have been furnished both by electrical transport and photoemission measurements, namely the increase in the conductivity, the shift of the threshold voltage and the shift of the T6 HOMO peak towards higher binding energies.

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supporting

confidence: 87%

Surface doping in T6/PDI-8CN2 heterostructures investigated by transport and photoemission measurements

Aversa

Verucchi

Tatti

et al. 2012

Applied Physics Letters

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“…absent Cl core-level signals) changes in the S2p spectrum due to residual solvent/PCPDTBT interactions can be ruled out. Although this observation is reminiscent of the related oligomer MTBT [4,7-bis(5-methylthiophen-2-yl)benzo[c] [1,2,5]thiadiazole], a model molecule for PCPDTBT, [29] the situation is generally different for both systems due to the different preparation methods. Even if PCPDTBT thin films were prepared ex situ from solution and MTBT was evaporated in situ on sputter-cleaned Au [29] a similar chemical interaction is found.…”

Section: Chemical Interaction Between Pcpdtbt and Aumentioning

confidence: 89%

Electronic Properties of Interfaces between PCPDTBT and Prototypical Electrodes Studied by Photoemission Spectroscopy

et al. 2011

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We report on the electronic structure of poly[2,6-(4,4-bis- (2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT), a promising low-band-gap donor material for efficient bulk heterojunction organic solar cells. Electronic properties of interfaces formed between PCPDTBT and prototypical electrodes [Au, indium-tin-oxide and poly(ethylene-dioxythiophene): poly(styrenesulfonate)], obtained from X-ray photoemission spectroscopy and ultraviolet photoemission spectroscopy, are evaluated. The formation of interface dipoles is observed, and their consequences for device performance are discussed. For the system PCPDTBT/Au chemical interactions occur, which may affect in particular the charge extraction at the corresponding interface.

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“…In the case of sulfur at least two new signals appear in the core-level spectra with binding energies of 168.8 and 169.3 eV (Figure 4 a). [30][31][32] The intensity ratio between oxidized and unoxidized components was determined by peak fitting of the XPS signal, assuming the same peak shape for all components. [30][31][32] The intensity ratio between oxidized and unoxidized components was determined by peak fitting of the XPS signal, assuming the same peak shape for all components.…”

Section: Product Evolution Studied By Xpsmentioning

confidence: 99%

“…These new signals can be assigned to highly oxidized sulfur species, probably sulfonic acids [29] or peroxides. [30][31][32] The intensity ratio between oxidized and unoxidized components was determined by peak fitting of the XPS signal, assuming the same peak shape for all components.…”

Section: Product Evolution Studied By Xpsmentioning

confidence: 99%

Photodegradation of C‐PCPDTBT and Si‐PCPDTBT: Influence of the Bridging Atom on the Stability of a Low‐Band‐Gap Polymer for Solar Cell Application

et al. 2014

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The kinetics of photodegradation and the reactivity of different sites of the low-band-gap polymers poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b']dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (C-PCPDTBT) and poly[2,6-(4,4-bis-(2-ethylhexyl)dithieno[3,2-b:2',3'-d]silole)-alt-4,7-(2,1,3-benzothiadiazole)] (Si-PCPDTBT) are investigated as thin films and are compared to those of poly(3-hexylthiophene) (P3HT). The decay kinetics are monitored with UV/Vis spectroscopy and the reactivity and product evolution are investigated with X-ray photoelectron spectroscopy (XPS). Both polymers exhibit higher stability than P3HT. The bridging atom in the cyclopentadithiophene (CPDT) subunit has a significant influence on the stability. Varying oxidation rates for the different elements were observed. In the case of Si-PCPDTBT, the silicon atom is oxidized primarily, whereas the photooxidation rates of the other elements are reduced relative to C-PCPDTBT. Additionally, XPS experiments with varying excitation energies reveal a significant reaction gradient within a few nanometers of the surface of degraded thin films of C-PCPDTBT.

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Electronic Structure and Interface Properties of a Model Molecule for Organic Solar Cells

Cited by 21 publications

References 36 publications

Surface doping in T6/PDI-8CN2 heterostructures investigated by transport and photoemission measurements

Surface doping in T6/PDI-8CN2 heterostructures investigated by transport and photoemission measurements

Electronic Properties of Interfaces between PCPDTBT and Prototypical Electrodes Studied by Photoemission Spectroscopy

Photodegradation of C‐PCPDTBT and Si‐PCPDTBT: Influence of the Bridging Atom on the Stability of a Low‐Band‐Gap Polymer for Solar Cell Application

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