What determines the performance of metal phthalocyanines (MPc, M=Zn, Cu, Ni, Fe) in organic heterojunction solar cells? A combined experimental and theoretical investigation

Bruder, Ingmar; Schöneboom, Jan; Dinnebiér, Robert E.; Ojala, Antti; Schäfer, Stefan; Sens, Rüdiger; Erk, Peter; Weis, J.

doi:10.1016/j.orgel.2009.11.016

Cited by 65 publications

(55 citation statements)

References 53 publications

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“…29,32,33 It suggests that ZnPc does not prefer bonding to defects, contrary to 4-tert-butyl pyridine that preferentially binds to oxygen vacancies. 31,34 Based on our theoretical calculations (Figure 1, right) and other simulation reports, 25,35 the HOMO of ZnPc is essentially the a 1u orbital with main contributions from pyrrole carbons, C P . Hence, when charge is removed a larger charge deficiency may be expected for the inner ring.…”

Section: Photoelectron Spectroscopysupporting

confidence: 55%

“…There are at least three aspects which may contribute to this scenario. Firstly, theoretical calculations 25,35 and experiments 7,8,64,67 predict and illustrate that the open shell Fe d−orbitals contribute to the HOMO and participate in the interaction with substrate or doping. However, the zinc metal center with filled d-orbitals is rather inert compared to Fe and less influenced by changes in the peripheral part of the molecule.…”

Section: Nexafsmentioning

confidence: 99%

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Inhomogeneous charge transfer within monolayer zinc phthalocyanine absorbed on TiO2(110)

Ahmadi

Sun

et al. 2012

The Journal of Chemical Physics

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Adsorption geometry, molecular interaction, and charge transfer of triphenylamine-based dye on rutile TiO2 (110) The d-orbital contribution from the transition metal centers of phthalocyanine brings difficulties to understand the role of the organic ligands and their molecular frontier orbitals when it adsorbs on oxide surfaces. Here we use zinc phthalocyanine (ZnPc)/TiO 2 (110) as a model system where the zinc d-orbitals are located deep below the organic orbitals leaving room for a detailed study of the interaction between the organic ligand and the substrate. A charge depletion from the highest occupied molecular orbital is observed, and a consequent shift of N1s and C1s to higher binding energy in photoelectron spectroscopy (PES). A detailed comparison of peak shifts in PES and near-edge X-ray absorption fine structure spectroscopy illustrates a slightly uneven charge distribution within the molecular plane and an inhomogeneous charge transfer screening between the center and periphery of the organic ligand: faster in the periphery and slower at the center, which is different from other metal phthalocyanine, e.g., FePc/TiO 2 . Our results indicate that the metal center can substantially influence the electronic properties of the organic ligand at the interface by introducing an additional charge transfer channel to the inner molecular part.

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Section: Photoelectron Spectroscopysupporting

confidence: 55%

Section: Nexafsmentioning

confidence: 99%

Inhomogeneous charge transfer within monolayer zinc phthalocyanine absorbed on TiO2(110)

Ahmadi

Sun

et al. 2012

The Journal of Chemical Physics

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“…ZnPc was chosen since it leads to higher cell efficiencies compared to other metal phthalocyanines. 26 We show, that ITO plasma treatment and/or altering the cell architecture causes an increase of V oc which we attribute to decreased recombination at the ITO/organic interface. A strong UV-induced cell degradation of illuminated ZnPc/C 60 cells under inert atmosphere is traced back to the same interface.…”

Section: Introductionmentioning

confidence: 68%

Influence of the indium tin oxide/organic interface on open-circuit voltage, recombination, and cell degradation in organic small-molecule solar cells

et al. 2011

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In this paper we investigate the performance and stability of small-molecule organic solar cells with respect to the indium tin oxide (ITO)/organic interface. Different zinc-phthalocyanine (ZnPc)/fullerene (C 60 ) cell architectures with and without ITO O 2 -plasma treatment are compared and tested with respect to their degradation behavior under illumination in inert atmosphere. Photoelectron spectroscopy (UPS and XPS) shows that the O 2 -plasma treatment increases the ITO work function from 4.3 eV up to 5.6 eV. We find that both the increased ITO work function as well as the introduction of an electron blocking layer between ITO and the mixed donor/acceptor layer increases the open-circuit voltage V oc by more than 200 mV. For both cases our continuum approach device simulation quantitatively relates the increase of V oc to a reduced contact recombination and thus a reduced dark current. For cells built on ozone treated ITO we find a fast cell degradation caused by the UV part of the AM 1.5 spectrum. We identify the degradation, which manifests itself in a decrease of V oc of up to 25%, as a partial reversion of the plasma induced ITO work function increase. Additionally, we demonstrate that the degradation can be reduced by structural changes in the cell architecture, leading to improved cell stability. We present a comprehensive study of the recombination at the ITO/organic interface and its influence on the open-circuit voltage and the cell stability.

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“…The zinc-centered molecules are the focus due to their superior performance as a leading MPc for absorption in OPVs amongst other possible metal centers. 31 Furthermore, the research into phenyl ring additions is due to the previously correlated research where the increase in steric bulk leads to better PCE. 13,32 This current research investigates all 8 of the molecules in Fig.…”

Section: Introductionmentioning

confidence: 99%

Ground and excited states of zinc phthalocyanine, zinc tetrabenzoporphyrin, and azaporphyrin analogs using DFT and TDDFT with Franck-Condon analysis

Theisen

Huang

Fleetham

et al. 2015

The Journal of Chemical Physics

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Articles you may be interested inGround and excited states of zinc phthalocyanine, zinc tetrabenzoporphyrin, and azaporphyrin analogs using DFT and TDDFT with Franck-Condon analysis The electronic structure of eight zinc-centered porphyrin macrocyclic molecules are investigated using density functional theory for ground-state properties, time-dependent density functional theory (TDDFT) for excited states, and Franck-Condon (FC) analysis for further characterization of the UV-vis spectrum. Symmetry breaking was utilized to find the lowest energy of the excited states for many states in the spectra. To confirm the theoretical modeling, the spectroscopic result from zinc phthalocyanine (ZnPc) is used to compare to the TDDFT and FC result. After confirmation of the modeling, five more planar molecules are investigated: zinc tetrabenzoporphyrin (ZnTBP), zinc tetrabenzomonoazaporphyrin (ZnTBMAP), zinc tetrabenzocisdiazaporphyrin (ZnTBcisDAP), zinc tetrabenzotransdiazaporphyrin (ZnTBtransDAP), and zinc tetrabenzotriazaporphyrin (ZnTBTrAP). The two latter molecules are then compared to their phenylated sister molecules: zinc monophenyltetrabenzotriazaporphyrin (ZnMPTBTrAP) and zinc diphenyltetrabenzotransdiazaporphyrin (ZnDPTBtransDAP). The spectroscopic results from the synthesis of ZnMPTBTrAP and ZnDPTBtransDAP are then compared to their theoretical models and nonphenylated pairs. While the Franck-Condon results were not as illuminating for every B-band, the Q-band results were successful in all eight molecules, with a considerable amount of spectral analysis in the range of interest between 300 and 750 nm. The π-π * transitions are evident in the results for all of the Q bands, while satellite vibrations are also visible in the spectra. In particular, this investigation finds that, while ZnPc has a D 4h symmetry at ground state, a C 4v symmetry is predicted in the excited-state Q band region. The theoretical results for ZnPc found an excitation energy at the Q-band 0-0 transition of 1.88 eV in vacuum, which is in remarkable agreement with published gas-phase spectroscopy, as well as our own results of ZnPc in solution with Tetrahydrofuran that are provided in this paper. C 2015 AIP Publishing LLC. [http://dx

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What determines the performance of metal phthalocyanines (MPc, M=Zn, Cu, Ni, Fe) in organic heterojunction solar cells? A combined experimental and theoretical investigation

Cited by 65 publications

References 53 publications

Inhomogeneous charge transfer within monolayer zinc phthalocyanine absorbed on TiO2(110)

Inhomogeneous charge transfer within monolayer zinc phthalocyanine absorbed on TiO2(110)

Influence of the indium tin oxide/organic interface on open-circuit voltage, recombination, and cell degradation in organic small-molecule solar cells

Ground and excited states of zinc phthalocyanine, zinc tetrabenzoporphyrin, and azaporphyrin analogs using DFT and TDDFT with Franck-Condon analysis

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