Zinc Phthalocyanine

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Hidenori Mimura - One of the best experts on this subject based on the ideXlab platform.

Karl Leo - One of the best experts on this subject based on the ideXlab platform.

  • Fluorinated Zinc Phthalocyanine as donor for efficient vacuum-deposited organic solar cells
    2012
    Co-Authors: Jan Meiss, Moritz Hein, Christoph Schuenemann, Max Tietze, Karl Leo, André Merten, Christian Uhrich, Martin Pfeiffer, Stefan Schafer, Mirko Riede
    Abstract:

    Efficient single bulk heterojunction organic solar cells based on blends of a fluorinated Zinc Phthalocyanine as electron donor and fullerene C60 as elec- tron acceptor are reported. In comparison to the commonly used absorber Zinc Phthalocyanine, the fluorination of the molecule to F4ZnPc leads to an increase in ionisation potential and subsequently to an improvement of about 170 mV in the open circuit voltage of organic solar cells, while the short circuit current density and fill factor remain nearly unchanged. Similar to ZnPc:C60-based devices, the device characteristics of F4ZnPc:C60 solar cells can be further enhanced by improving the blend layer morphology by substrate heating during deposition. F4ZnPc is an efficient donor material that can achieve a 4.6% power conversion efficiency in single heterojunction organic solar cells.

  • Zinc Phthalocyanine influence of substrate temperature film thickness and kind of substrate on the morphology
    2011
    Co-Authors: Christoph Schunemann, Karl Leo, Chris Elschner, A A Levin, Marieta Levichkova, Moritz Riede
    Abstract:

    Abstract Zinc Phthalocyanine (ZnPc), C32H16N8Zn, is a planar organic molecule having numerous optical and electrical applications in organic electronics. This work investigates the influence of various deposition parameters on the morphology of vapour thermal evaporated ZnPc films. For this purpose, ZnPc is deposited at different substrate temperatures up to 90 °C and film thickness up to 50 nm onto various substrates. The morphology of this ZnPc layers is characterised by X-ray diffraction (XRD), X-ray reflectivity (XRR) and atomic force microscopy (AFM) methods. XRD measurements show that all ZnPc films are crystalline in a triclinic (α-ZnPc) or monoclinic (γ-ZnPc) phase, independent from the kind of substrate, layer thickness, or substrate temperature. The ZnPc powder, the starting product for the thermally evaporated ZnPc films, is present in the stable monoclinic β-phase. Thus, the stacking of the ZnPc molecules changes completely during deposition. The crystallite size perpendicular to the substrate determined by XRD microstructure analysis is in the range of the layer thickness while the lateral size, obtained by AFM, is increasing with substrate temperature and film thickness. AFM and XRR show an increase of the layer roughness for thicker ZnPc layers and higher substrate temperatures during film deposition. The strain in the ZnPc films decreases for higher substrate temperatures due to enhanced thermal relaxation and for thicker ZnPc films due to lower surface tension.

  • aging of flat heterojunction Zinc Phthalocyanine fullerene c60 organic solar cells
    2010
    Co-Authors: R Lessmann, Moritz Riede, Z R Hong, B Maennig, Sebastian Scholz, Karl Leo
    Abstract:

    Abstract This work addresses the long-term aging of organic solar cells based on a flat Zinc Phthalocyanine (ZnPc)/C60 heterojunction. We investigate both the typical degradation behavior of the short circuit current and of the saturated photocurrent, defined as I(−1V). The latter remains constant after a relatively small initial decay, which is directly related to a substantial reduction of the contribution of excitons generated in C60 to the external quantum efficiency. Mass spectroscopy analysis of the organic material after aging revealed oxidized C60 and sub-products thereof. The reduction of I(−1V) is thus attributed to the reaction of C60 molecules with oxygen impurities. The results strongly suggest that ZnPc/C60 photovoltaic cells are intrinsically very stable on a time scale of thousand of hours if such reactions are prevented.

  • antenna effects and improved efficiency in multiple heterojunction photovoltaic cells based on pentacene Zinc Phthalocyanine and c60
    2009
    Co-Authors: Z R Hong, Moritz Riede, B Maennig, R Lessmann, Q Huang, Kentaro Harada, Karl Leo
    Abstract:

    For organic solar cells, effective absorption over a wide wavelength range is important. A simple donor-acceptor pair is usually not sufficient to reach this goal. Thus, it would be desirable to utilize multiple photoactive materials in a single cell. In this work, two hole conducting materials, pentacene and Zinc Phthalocyanine (ZnPc), and electron conducting C60 are chosen to construct three-component heterojunctions aiming at improved effective photon harvesting in organic solar cells. It is found that in pentacene/ZnPc/C60 multiple heterojunctions, part of the excitons in pentacene reach the ZnPc/C60 interface, where efficient exciton separation occurs and contributes to the photocurrent (PC). Triplet excitons are confirmed to be the major origin of PC by transient PC response measurements, suggesting that triplet-to-triplet energy transfer from pentacene to ZnPc is responsible for the improved PC of pentacene/ZnPc/C60 multiheterojunctions. Furthermore, exothermic energy transfer from ZnPc to the lowe...

  • improved efficiency of Zinc Phthalocyanine c60 based photovoltaic cells via nanoscale interface modification
    2007
    Co-Authors: Z R Hong, Karl Leo, Martin Pfeiffer, B Maennig, R Lessmann, Paul Simon
    Abstract:

    The photovoltaic performance of Zinc Phthalocyanine (ZnPc)∕C60 heterojunctions is improved by alternately depositing ultrathin active layers between the two bulk layers. Using a proper multilayer structure, a 60% improvement in conversion efficiency under AM1.5 illumination is obtained, in comparison with that of flat heterojunctions. Transmission electron microscope investigations reveal an effective phase separation of ZnPc and C60 and a high degree of crystalline ordering of C60 in this system. The authors propose that an interpenetrating interface is formed, which facilitates both exciton separation and charge transport, and enhances the photocurrent from ZnPc due to an extended photoactive region.The photovoltaic performance of Zinc Phthalocyanine (ZnPc)∕C60 heterojunctions is improved by alternately depositing ultrathin active layers between the two bulk layers. Using a proper multilayer structure, a 60% improvement in conversion efficiency under AM1.5 illumination is obtained, in comparison with that of flat heterojunctions. Transmission electron microscope investigations reveal an effective phase separation of ZnPc and C60 and a high degree of crystalline ordering of C60 in this system. The authors propose that an interpenetrating interface is formed, which facilitates both exciton separation and charge transport, and enhances the photocurrent from ZnPc due to an extended photoactive region.

Shunichi Fukuzumi - One of the best experts on this subject based on the ideXlab platform.

  • a two point bound Zinc porphyrin Zinc Phthalocyanine fullerene supramolecular triad for sequential energy and electron transfer
    2013
    Co-Authors: Kei Ohkubo, Shunichi Fukuzumi, Paul A Karr, Francis Dsouza
    Abstract:

    A novel supramolecular triad composed of a Zinc porphyrin–Zinc Phthalocyanine dyad and fullerenes has been assembled using a ‘two-point’ axial binding approach, and occurrence of efficient photoinduced energy transfer followed by electron transfer is demonstrated.

  • self assembled via metal ligand coordination azabodipy Zinc Phthalocyanine and azabodipy Zinc naPhthalocyanine conjugates synthesis structure and photoinduced electron transfer
    2013
    Co-Authors: Venugopal Bandi, Shunichi Fukuzumi, Paul A Karr, Mohamed E Elkhouly, Vladimir N Nesterov, Francis Dsouza
    Abstract:

    Using near-IR emitting photosensitizers, viz., Zinc Phthalocyanine (ZnPc), Zinc naPhthalocyanine (ZnNc), and BF2-chelated azadipyrromethene (azaBODIPY), donor–acceptor conjugates have been newly formed using the well-known metal–ligand axial coordination approach. To accomplish this task, the electron-deficient azaBODIPY was functionalized to possess either two pyridine or imidazole ligating entities. The X-ray crystal structure of one such derivative revealed the presence of axial binding capable pyridine entities on the azaBODIPY macrocycle. The structural integrity of the newly formed conjugates was established from optical absorption, emission, 1H NMR, electrochemical, and computational methods. The experimentally determined binding constants suggested moderately stable conjugates. The absence of excitation energy transfer from singlet excited azaBODIPY to either ZnPc or ZnNc in the conjugates was confirmed from the steady-state emission measurements. However, free-energy calculations suggested photoi...

  • Zinc Phthalocyanine graphene hybrid material for energy conversion synthesis characterization photophysics and photoelectrochemical cell preparation
    2012
    Co-Authors: Nikolaos Karousis, Javier Ortiz, Angela Sastresantos, Shunichi Fukuzumi, Kei Ohkubo, Taku Hasobe, Nikos Tagmatarchis
    Abstract:

    Graphene exfoliation upon tip sonication in o-dichlorobenzene (o-DCB) was accomplished. Covalent grafting of (2-aminoethoxy)(tri-tert-butyl) Zinc Phthalocyanine (ZnPc) to exfoliated graphene sheets was then achieved. The newly formed ZnPc–graphene hybrid material was found to be soluble in common organic solvents without any precipitation for several weeks. Application of diverse spectroscopic techniques verified the successful formation of the ZnPc–graphene hybrid material, while thermogravimetric analysis revealed the amount of ZnPc loading onto graphene. Microscopy analysis based on AFM and TEM was applied to probe the morphological characteristics and to investigate the exfoliation of graphene sheets. Efficient fluorescence quenching of ZnPc in the ZnPc–graphene hybrid material suggested that photoinduced events occur from the photoexcited ZnPc to exfoliated graphene. The dynamics of the photoinduced electron transfer was evaluated by femtosecond transient absorption spectroscopy, thus revealing the f...

  • photosynthetic reaction center mimicry low reorganization energy driven charge stabilization in self assembled cofacial Zinc Phthalocyanine dimer fullerene conjugate
    2009
    Co-Authors: Francis Dsouza, Kei Ohkubo, Eranda Maligaspe, Melvin E Zandler, Navaneetha K Subbaiyan, Shunichi Fukuzumi
    Abstract:

    By employing well-defined self-assembly methods, a biomimetic bacterial photosynthetic reaction center complex has been constructed, and photoinduced electron transfer originating in this supramolecular donor−acceptor conjugate has been investigated. The biomimetic model of the bacterial “special pair” donor, a cofacial Zinc Phthalocyanine dimer, was formed via potassium ion induced dimerization of 4,5,4′,5′,4′′, 5′′,4′′′,5′′′-Zinc tetrakis(1,4,7,10,13-pentaoxatridecamethylene)Phthalocyanine. The dimer was subsequently self-assembled with functionalized fullerenes via “two-point” binding involving axial coordination and crown ether-alkyl ammonium cation complexation to form the donor−acceptor pair, mimicking the noncovalently bound entities of the bacterial photosynthetic reaction center. The adopted self-assembly methodology yielded a supramolecular complex of higher stability with defined geometry and orientation as revealed by the binding constant and computational optimized structure. Unlike the previ...

  • control of photoinduced electron transfer in Zinc Phthalocyanine perylenediimide dyad and triad by the magnesium ion
    2008
    Co-Authors: Shunichi Fukuzumi, Javier Ortiz, Fernando Fernandezlazaro, Angela Sastresantos, Kei Ohkubo, Ana M Gutierrez
    Abstract:

    Photoexcitation of a Zinc Phthalocyanine−perylenediimide (ZnPc−PDI) dyad and a bis(Zinc Phthalocyanine)−perylenediimide [(ZnPc)2−PDI] triad results in formation of the triplet excited state of the PDI moiety without the fluorescence emission, whereas addition of Mg2+ ions to the dyad and triad results in formation of long-lived charge-separated (CS) states (ZnPc•+−PDI•−/Mg2+ and (ZnPc)2•+−PDI•−/Mg2+) in which PDI•− forms a complex with Mg2+. Formation of the CS states in the presence of Mg2+ was confirmed by appearance of the absorption bands due to ZnPc•+ and PDI•−/Mg2+ complex in the time-resolved transient absorption spectra of the dyad and triad. The one-electron reduction potential (Ered) of the PDI moiety in the presence of a metal ion is shifted to a positive direction due to the binding of Mg2+ to PDI•−, whereas the one-electron oxidation potential of the ZnPc moiety remains the same. The binding of Mg2+ to PDI•− was confirmed by the ESR spectrum, which is different from that of PDI•− without Mg2+...

Francis Dsouza - One of the best experts on this subject based on the ideXlab platform.

  • excited state charge transfer in covalently functionalized mos2 with a Zinc Phthalocyanine donor acceptor hybrid
    2019
    Co-Authors: Ruben Cantonvitoria, Habtom B Gobeze, Vicente M Blasferrando, Javier Ortiz, Youngwoo Jang, Fernando Fernandezlazaro, Angela Sastresantos, Yusuke Nakanishi, Hisanori Shinohara, Francis Dsouza
    Abstract:

    : The functionalization of MoS2 is of paramount importance for tailoring its properties towards optoelectronic applications and unlocking its full potential. Zinc Phthalocyanine (ZnPc) carrying an 1,2-dithiolane oxide linker was used to functionalize MoS2 at defect sites located at the edges. The structure of ZnPc-MoS2 was fully assessed by complementary spectroscopic, thermal, and microscopy imaging techniques. An energy-level diagram visualizing different photochemical events in ZnPc-MoS2 was established and revealed a bidirectional electron transfer leading to a charge separated state ZnPc.+ -MoS2.- . Markedly, evidence of the charge transfer in the hybrid material was demonstrated using fluorescence spectroelectrochemistry. Systematic studies performed by femtosecond transient absorption revealed the involvement of excitons generated in MoS2 in promoting the charge transfer, while the transfer was also possible when ZnPc was excited, signifying their potential in light-energy-harvesting devices.

  • a two point bound Zinc porphyrin Zinc Phthalocyanine fullerene supramolecular triad for sequential energy and electron transfer
    2013
    Co-Authors: Kei Ohkubo, Shunichi Fukuzumi, Paul A Karr, Francis Dsouza
    Abstract:

    A novel supramolecular triad composed of a Zinc porphyrin–Zinc Phthalocyanine dyad and fullerenes has been assembled using a ‘two-point’ axial binding approach, and occurrence of efficient photoinduced energy transfer followed by electron transfer is demonstrated.

  • self assembled via metal ligand coordination azabodipy Zinc Phthalocyanine and azabodipy Zinc naPhthalocyanine conjugates synthesis structure and photoinduced electron transfer
    2013
    Co-Authors: Venugopal Bandi, Shunichi Fukuzumi, Paul A Karr, Mohamed E Elkhouly, Vladimir N Nesterov, Francis Dsouza
    Abstract:

    Using near-IR emitting photosensitizers, viz., Zinc Phthalocyanine (ZnPc), Zinc naPhthalocyanine (ZnNc), and BF2-chelated azadipyrromethene (azaBODIPY), donor–acceptor conjugates have been newly formed using the well-known metal–ligand axial coordination approach. To accomplish this task, the electron-deficient azaBODIPY was functionalized to possess either two pyridine or imidazole ligating entities. The X-ray crystal structure of one such derivative revealed the presence of axial binding capable pyridine entities on the azaBODIPY macrocycle. The structural integrity of the newly formed conjugates was established from optical absorption, emission, 1H NMR, electrochemical, and computational methods. The experimentally determined binding constants suggested moderately stable conjugates. The absence of excitation energy transfer from singlet excited azaBODIPY to either ZnPc or ZnNc in the conjugates was confirmed from the steady-state emission measurements. However, free-energy calculations suggested photoi...

  • sequential photoinduced energy and electron transfer directed improved performance of the supramolecular solar cell of a Zinc porphyrin Zinc Phthalocyanine conjugate modified tio2 surface
    2013
    Co-Authors: Kati Stranius, Navaneetha K Subbaiyan, Preston Dsouza, Helge Lemmetyinen, Nikolai V Tkachenko, Francis Dsouza
    Abstract:

    Improved performance of a photosynthetic antenna–reaction center mimicking supramolecular solar cell is demonstrated. Toward this, porphyrin–Phthalocyanine conjugates connected by amide linkers, as wide-band capturing solar energy harvesting materials, have been newly synthesized and characterized. Efficient singlet–singlet energy transfer from the Zinc or free-base porphyrin to Phthalocyanine is evidenced from steady-state emission and transient absorption studies in nonpolar and polar solvents. Further, the dyad was immobilized via axial coordination of Zinc porphyrin of the dyad on semiconducting TiO2 surface modified with axial coordinating ligand functionality, phenylimidazole. Photoelectrochemical studies revealed improved performance of this cell compared to either Zinc porphyrin or Zinc Phthalocyanine only modified electrodes under similar experimental conditions. Transient absorption studies performed on the dyad immobilized on glass/TiO2 surface suggested that upon excitation of the axially coor...

  • photosynthetic reaction center mimicry low reorganization energy driven charge stabilization in self assembled cofacial Zinc Phthalocyanine dimer fullerene conjugate
    2009
    Co-Authors: Francis Dsouza, Kei Ohkubo, Eranda Maligaspe, Melvin E Zandler, Navaneetha K Subbaiyan, Shunichi Fukuzumi
    Abstract:

    By employing well-defined self-assembly methods, a biomimetic bacterial photosynthetic reaction center complex has been constructed, and photoinduced electron transfer originating in this supramolecular donor−acceptor conjugate has been investigated. The biomimetic model of the bacterial “special pair” donor, a cofacial Zinc Phthalocyanine dimer, was formed via potassium ion induced dimerization of 4,5,4′,5′,4′′, 5′′,4′′′,5′′′-Zinc tetrakis(1,4,7,10,13-pentaoxatridecamethylene)Phthalocyanine. The dimer was subsequently self-assembled with functionalized fullerenes via “two-point” binding involving axial coordination and crown ether-alkyl ammonium cation complexation to form the donor−acceptor pair, mimicking the noncovalently bound entities of the bacterial photosynthetic reaction center. The adopted self-assembly methodology yielded a supramolecular complex of higher stability with defined geometry and orientation as revealed by the binding constant and computational optimized structure. Unlike the previ...

Angela Sastresantos - One of the best experts on this subject based on the ideXlab platform.

  • excited state charge transfer in covalently functionalized mos2 with a Zinc Phthalocyanine donor acceptor hybrid
    2019
    Co-Authors: Ruben Cantonvitoria, Habtom B Gobeze, Vicente M Blasferrando, Javier Ortiz, Youngwoo Jang, Fernando Fernandezlazaro, Angela Sastresantos, Yusuke Nakanishi, Hisanori Shinohara, Francis Dsouza
    Abstract:

    : The functionalization of MoS2 is of paramount importance for tailoring its properties towards optoelectronic applications and unlocking its full potential. Zinc Phthalocyanine (ZnPc) carrying an 1,2-dithiolane oxide linker was used to functionalize MoS2 at defect sites located at the edges. The structure of ZnPc-MoS2 was fully assessed by complementary spectroscopic, thermal, and microscopy imaging techniques. An energy-level diagram visualizing different photochemical events in ZnPc-MoS2 was established and revealed a bidirectional electron transfer leading to a charge separated state ZnPc.+ -MoS2.- . Markedly, evidence of the charge transfer in the hybrid material was demonstrated using fluorescence spectroelectrochemistry. Systematic studies performed by femtosecond transient absorption revealed the involvement of excitons generated in MoS2 in promoting the charge transfer, while the transfer was also possible when ZnPc was excited, signifying their potential in light-energy-harvesting devices.

  • Zinc Phthalocyanine graphene hybrid material for energy conversion synthesis characterization photophysics and photoelectrochemical cell preparation
    2012
    Co-Authors: Nikolaos Karousis, Javier Ortiz, Angela Sastresantos, Shunichi Fukuzumi, Kei Ohkubo, Taku Hasobe, Nikos Tagmatarchis
    Abstract:

    Graphene exfoliation upon tip sonication in o-dichlorobenzene (o-DCB) was accomplished. Covalent grafting of (2-aminoethoxy)(tri-tert-butyl) Zinc Phthalocyanine (ZnPc) to exfoliated graphene sheets was then achieved. The newly formed ZnPc–graphene hybrid material was found to be soluble in common organic solvents without any precipitation for several weeks. Application of diverse spectroscopic techniques verified the successful formation of the ZnPc–graphene hybrid material, while thermogravimetric analysis revealed the amount of ZnPc loading onto graphene. Microscopy analysis based on AFM and TEM was applied to probe the morphological characteristics and to investigate the exfoliation of graphene sheets. Efficient fluorescence quenching of ZnPc in the ZnPc–graphene hybrid material suggested that photoinduced events occur from the photoexcited ZnPc to exfoliated graphene. The dynamics of the photoinduced electron transfer was evaluated by femtosecond transient absorption spectroscopy, thus revealing the f...

  • control of photoinduced electron transfer in Zinc Phthalocyanine perylenediimide dyad and triad by the magnesium ion
    2008
    Co-Authors: Shunichi Fukuzumi, Javier Ortiz, Fernando Fernandezlazaro, Angela Sastresantos, Kei Ohkubo, Ana M Gutierrez
    Abstract:

    Photoexcitation of a Zinc Phthalocyanine−perylenediimide (ZnPc−PDI) dyad and a bis(Zinc Phthalocyanine)−perylenediimide [(ZnPc)2−PDI] triad results in formation of the triplet excited state of the PDI moiety without the fluorescence emission, whereas addition of Mg2+ ions to the dyad and triad results in formation of long-lived charge-separated (CS) states (ZnPc•+−PDI•−/Mg2+ and (ZnPc)2•+−PDI•−/Mg2+) in which PDI•− forms a complex with Mg2+. Formation of the CS states in the presence of Mg2+ was confirmed by appearance of the absorption bands due to ZnPc•+ and PDI•−/Mg2+ complex in the time-resolved transient absorption spectra of the dyad and triad. The one-electron reduction potential (Ered) of the PDI moiety in the presence of a metal ion is shifted to a positive direction due to the binding of Mg2+ to PDI•−, whereas the one-electron oxidation potential of the ZnPc moiety remains the same. The binding of Mg2+ to PDI•− was confirmed by the ESR spectrum, which is different from that of PDI•− without Mg2+...

  • formation of a long lived charge separated state of a Zinc Phthalocyanine perylenediimide dyad by complexation with magnesium ion
    2005
    Co-Authors: Shunichi Fukuzumi, Javier Ortiz, Fernando Fernandezlazaro, Angela Sastresantos, Kei Ohkubo, Ana M Gutierrez
    Abstract:

    Photoexcitation of a Zinc Phthalocyanine-perylenediimide (ZnPc-PDI) dyad affords the triplet excited state without the fluorescence emission, whereas addition of Mg2+ to the photoexcited ZnPc-PDI results in formation of a long-lived charge-separated state (ZnPc.+-PDI.-/Mg2+) in which PDI.- forms a complex with Mg2+.

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