Understanding the Interface Dipole of Copper Phthalocyanine (CuPc)/C<sub>60</sub>: Theory and Experiment

Sai, Na; Gearba, Raluca I.; Dolocan, Andrei; Tritsch, John R.; Chan, Wai‐Lun; Chelikowsky, James R.; Leung, Kevin; Zhu, Xiaoyang

doi:10.1021/jz300744r

Cited by 67 publications

(65 citation statements)

References 37 publications

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“…the amount of excess of charge obtained from integrating ∆ρ from the origin to the point where charge depletion switches to charge accumulation; n = 1/A, where A is the surface area of the interface). 30 The values of ∆Φ ~0.09 and ~0.04 eV obtained for Spiro-OMeTAD/CH 3 NH 3 PbI 3 and PCBM/CH 3 NH 3 PbI 3 system are somewhat smaller than the interfacial dipole barriers observed in experiments due to the monolayer thickness used in simulations, however the relative magnitude of electron and hole interfacial dipoles is well reproduced. Therefore we are confident that our hybrid interfacial model could be widely applied to search for new charge transporting materials to overcome the charge extraction bottleneck in hybrid perovskite solar cells.…”

mentioning

confidence: 84%

Interfacial Charge Transfer Anisotropy in Polycrystalline Lead Iodide Perovskite Films

Yin

Cortecchia

Krishna

et al. 2015

J. Phys. Chem. Lett.

145

141

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Solar cells based on organic-inorganic lead iodide perovskite (CH3NH3PbI3) exhibit remarkably high power conversion efficiency (PCE). One of the key issues in solution-processed films is that often the polycrystalline domain orientation is not well-defined, which makes it difficult to predict energy alignment and charge transfer efficiency. Here we combine ab initio calculations and photoelectron spectroscopy to unravel the electronic structure and charge redistribution at the interface between different surfaces of CH3NH3PbI3 and typical organic hole acceptor Spiro-OMeTAD and electron acceptor PCBM. We find that both hole and electron interfacial transfer depend strongly on the CH3NH3PbI3 surface orientation: while the (001) and (110) surfaces tend to favor hole injection to Spiro-OMeTAD, the (100) surface facilitates electron transfer to PCBM due to surface delocalized charges and hole/electron accumulation at the CH3NH3PbI3/organic interfaces. Molecular dynamic simulations indicate that this is due to strong orbital interactions under thermal fluctuations at room temperature, suggesting the possibility to further improve charge separation and extraction in perovskite-based solar cells by controlling perovskite film crystallization and surface orientation.

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mentioning

confidence: 84%

Interfacial Charge Transfer Anisotropy in Polycrystalline Lead Iodide Perovskite Films

Yin

Cortecchia

Krishna

et al. 2015

J. Phys. Chem. Lett.

145

141

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“…An ION-TOF TOF-SIMS.5 was used with a pulsed (18 ns, 10 kHz) analysis ion beam consisting of Bi 3 + clusters at 30-kV ion energy, which was raster-scanned over areas that typically varied between 100 × 100 μm 2 and 500 × 500 μm 2 , depending on the quality (i.e., corrugation and conductivity) of the sample surface. The polyatomic sputtering was selected to further enhance the signal and reduce fragmentation of large organic molecules (43)(44)(45). To reduce the sputtering-induced sample charging, a constant energy (21 eV) electron beam was shot on the sample during the data acquisition.…”

Section: Methodsmentioning

confidence: 99%

Chemical, experimental, and morphological evidence for diagenetically altered melanin in exceptionally preserved fossils

Colleary

Dolocan²,

Gardner

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

101

170

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In living organisms, color patterns, behavior, and ecology are closely linked. Thus, detection of fossil pigments may permit inferences about important aspects of ancient animal ecology and evolution. Melanin-bearing melanosomes were suggested to preserve as organic residues in exceptionally preserved fossils, retaining distinct morphology that is associated with aspects of original color patterns. Nevertheless, these oblong and spherical structures have also been identified as fossilized bacteria. To date, chemical studies have not directly considered the effects of diagenesis on melanin preservation, and how this may influence its identification. Here we use time-of-flight secondary ion mass spectrometry to identify and chemically characterize melanin in a diverse sample of previously unstudied extant and fossil taxa, including fossils with notably different diagenetic histories and geologic ages. We document signatures consistent with melanin preservation in fossils ranging from feathers, to mammals, to amphibians. Using principal component analyses, we characterize putative mixtures of eumelanin and phaeomelanin in both fossil and extant samples. Surprisingly, both extant and fossil amphibians generally exhibit melanosomes with a mixed eumelanin/phaeomelanin composition rather than pure eumelanin, as assumed previously. We argue that experimental maturation of modern melanin samples replicates diagenetic chemical alteration of melanin observed in fossils. This refutes the hypothesis that such fossil microbodies could be bacteria, and demonstrates that melanin is widely responsible for the organic soft tissue outlines in vertebrates found at exceptional fossil localities, thus allowing for the reconstruction of certain aspects of original pigment patterns.

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“…For instance, in terms of rangeseparated hybrid functionals 28,76,77 to correctly describe frontier orbitals, ionization potentials, electron affinities in terms of optimally tuned switching parameters. Both initial ground state and subsequent excited-state calculations have been performed using LDA approach as it gives consistence on the solution of the Kohn-Sham equations at both levels of the theory, without the inclusion of energy differences if a different functional is used in a previous calculation.…”

Section: Methodsmentioning

confidence: 99%

Ultrafast charge-transfer in organic photovoltaic interfaces: geometrical and functionalization effects

Santos

Wang

2016

Nanoscale

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Understanding the microscopic mechanisms of electronic excitation in organic photovoltaic cells is a challenging problem in the design of efficient devices capable of performing sunlight harvesting. Here we develop and apply an ab initio approach based on time-dependent density functional theory and Ehrenfest dynamics to investigate photoinduced charge transfer in small organic molecules. Our calculations include mixed quantum-classical dynamics with ions moving classically and electrons quantum mechanically, where no experimental external parameter other than the material geometry is required. We show that the behavior of photocarriers in zinc phthalocyanine (ZnPc) and C60 systems, an effective prototype system for organic solar cells, is sensitive to the atomic orientation of the donor and the acceptor units as well as the functionalization of covalent molecules at the interface. In particular, configurations with the ZnPc molecules facing on C60 facilitate charge transfer between substrate and molecules that occurs within 200 fs. In contrast, configurations where ZnPc is tilted above C60 present extremely low carrier injection efficiency even at longer times as an effect of the larger interfacial potential level offset and higher energetic barrier between the donor and acceptor molecules. An enhancement of charge injection into C60 at shorter times is observed as binding groups connect ZnPc and C60 in a dyad system. Our results demonstrate a promising way of designing and controlling photoinduced charge transfer on the atomic level in organic devices that would lead to efficient carrier separation and maximize device performance.

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Understanding the Interface Dipole of Copper Phthalocyanine (CuPc)/C₆₀: Theory and Experiment

Cited by 67 publications

References 37 publications

Interfacial Charge Transfer Anisotropy in Polycrystalline Lead Iodide Perovskite Films

Interfacial Charge Transfer Anisotropy in Polycrystalline Lead Iodide Perovskite Films

Chemical, experimental, and morphological evidence for diagenetically altered melanin in exceptionally preserved fossils

Ultrafast charge-transfer in organic photovoltaic interfaces: geometrical and functionalization effects

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Understanding the Interface Dipole of Copper Phthalocyanine (CuPc)/C60: Theory and Experiment

Cited by 67 publications

References 37 publications

Interfacial Charge Transfer Anisotropy in Polycrystalline Lead Iodide Perovskite Films

Interfacial Charge Transfer Anisotropy in Polycrystalline Lead Iodide Perovskite Films

Chemical, experimental, and morphological evidence for diagenetically altered melanin in exceptionally preserved fossils

Ultrafast charge-transfer in organic photovoltaic interfaces: geometrical and functionalization effects

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Product

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Understanding the Interface Dipole of Copper Phthalocyanine (CuPc)/C₆₀: Theory and Experiment