球烯C60与锌酞菁形成电荷迁移络合物的研究

球烯是一种很有前途的新型非线性光学材料，它具有非平面的共轭离域大Π键体系，具有结合电子的能力，可作为电子受体与电子给体形成电荷迁移络合物（CTC），并能改善有机分子的光学和电学性质[1~4]．金属酞青（MPc）也具有共轭大Π键体系，富有π电子，且具有良好的光敏性、化学稳定性及热稳定性．在一定条件下，球烯与金属酞育形成的CTC将大大改善金属酞育的光电性能．因此，研究球烯与金属酞蓄形成的CTC对开拓球烯与金属酞警的应用有重要意义．本文根据C60与锌酞菁（ZnPc）形成的CTC的光谱特征对其组成及相应的平衡常数进行了研究…     

Nanoscale organization of a phthalocyanine-fullerene system: remarkable stabilization of charges in photoactive 1-D nanotubules

Induction of self-organization between zinc phthalocyanine (ZnPc) and C60 moieties in a novel amphiphilic ZnPc-C60 salt results in uniformly nanostructured 1-D nanotubules. Their photoreactivity, in terms of ultrafast charge separation (i.e., approximately 1012 s-1) and ultraslow charge recombination (i.e., approximately 103 s-1), is remarkable. In addition, the observed ZnPc*+-C60*- lifetime of 1.4 ms implies, relative to that of the monomeric ZnPc-C60 ( approximately 3 ns), an impressive stabilization of 6 orders of magnitude.     

Control of photoinduced electron transfer in zinc phthalocyanine-perylenediimide dyad and triad by the magnesium ion

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 Mg (2+) ions to the dyad and triad results in formation of long-lived charge-separated (CS) states (ZnPc (*+)-PDI (*-)/Mg (2+) and (ZnPc) 2 (*+)-PDI (*-)/Mg (2+)) in which PDI (*-) forms a complex with Mg (2+). Formation of the CS states in the presence of Mg (2+) was confirmed by appearance of the absorption bands due to ZnPc (*+) and PDI (*-)/Mg (2+) complex in the time-resolved transient absorption spectra of the dyad and triad. The one-electron reduction potential ( E red) of the PDI moiety in the presence of a metal ion is shifted to a positive direction due to the binding of Mg (2+) to PDI (*-), whereas the one-electron oxidation potential of the ZnPc moiety remains the same. The binding of Mg (2+) to PDI (*-) was confirmed by the ESR spectrum, which is different from that of PDI (*-) without Mg (2+). The energy of the CS state (ZnPc (*+)-PDI (*-)/Mg (2+)) is determined to be 0.79 eV, which becomes lower that of the triplet excited state (ZnPc- (3)PDI*: 1.07 eV). This is the reason why the long-lived CS states were attained in the presence of Mg (2+) instead of the triplet excited state of the PDI moiety.     

Synthesis and photoinduced electron-transfer properties of phthalocyanine-[60]fullerene conjugates

A series of three novel ZnPc-C60 conjugates (Pc=phthalocyanine) 1 a-c bearing different spacers (single, double, and triple bond) between the two electroactive moieties was synthesized and compared to that of ZnPc-C60 conjugate 2, in which the two electroactive moieties are linked directly. The synthetic strategy- towards the preparation of 1 a-c- involved palladium-catalyzed cross-coupling reactions over a monoiodophthalocyanine precursor 4 to introduce the corresponding spacer, and subsequent dipolar cycloaddition reaction to C60. Detailed photophysical investigations of 1 a-c and 2 prompted an intramolecular electron transfer that evolves from the photoexcited ZnPc to the electron-accepting C60. In particular, with the help of femtosecond laser photolysis charge separation was indeed confirmed as the major deactivation channel. Complementary time-dependent density functional calculations supported the spectral assignment, namely, the spectral identity of the ZnPc(*+) radical cation and the C60 (*-) radical anion as seen in the differential absorption spectra. The lifetimes of the correspondingly formed radical ion-pair states depend markedly on the solvent polarity: they increase as polarity decreases. Similarly, although to a lesser extent, the nature of the linker impacts the lifetime of the radical ion-pair states. In general, the lifetimes of these states tend to be shortest in the system that lacks any spacer at all (2), whereas the longest lifetimes were found in the system that carries the triple-bond spacer (1 a).     

Synthesis,Photophysical and Electrochemical Properties of Amide‐Linked Phthalocyanine‐Fullerene Dyad

A new amide‐linked phthalocyanine‐fullerene dyad ZnPc‐C₆₀ was synthesized and characterized. The photophysical and electrochemical properties of the ZnPc‐C₆₀ dyad were investigated. The fluorescence spectrum and quantum yield in different solvents showed the occurrence of photoinduced electron transfer (PET) from the singlet excited ZnPc to C₆₀, which was further confirmed by nanosecond transient absorption spectra and cyclic voltammetry data. The free energy change for charge separation (ΔG_CS) was estimated to be exothermic with ?0.51 eV, which favored the formation of charge‐separation state. The PET from ZnPc to C₆₀ in ZnPc‐C₆₀ made the dyad exhibit stronger reverse saturable absorption performance compared with C₆₀ and the control sample in the Z‐scan experiments, which indicated the synergistic effect of two active moieties in the dyad.     

Sequential,Ultrafast Energy Transfer and Electron Transfer in a Fused Zinc Phthalocyanine-free-base Porphyrin-C60 Supramolecular Triad

A supramolecular triad composed of a fused zinc phthalocyanine-free-base porphyrin dyad (ZnPc-H₂P) coordinated to phenylimidazole functionalized C₆₀ via metal-ligand axial coordination was assembled, as a photosynthetic antenna-reaction centre mimic. The process of self-assembly resulting into the formation of C₆₀Im:ZnPc-H₂P supramolecular triad was probed by proton NMR, UV-Visible and fluorescence experiments at ambient temperature. The geometry and electronic structures were deduced from DFT calculations performed at the B3LYP/6-31G(dp) level. Electrochemical studies revealed ZnPc to be a better electron donor compared to H₂P, and C₆₀ to be the terminal electron acceptor. Fluorescence studies of the ZnPc-H₂P dyad revealed excitation energy transfer from ¹H₂P* to ZnPc within the fused dyad and was confirmed by femtosecond transient absorption studies. Similar to that reported earlier for the fused ZnPc-ZnP dyad, the energy transfer rate constant, k_ENT was in the order of 10¹² s⁻¹ in the ZnPc-H₂P dyad indicating an efficient process as a consequence of direct fusion of the two π-systems. In the presence of C₆₀Im bound to ZnPc, photoinduced electron transfer leading to H₂P-ZnPc^.+:ImC₆₀^.− charge separated state was observed either by selective excitation of ZnPc or H₂P. The latter excitation involved an energy transfer followed by electron transfer mechanism. Nanosecond transient absorption studies revealed that the lifetime of charge separated state persists for about 120 ns indicating charge stabilization in the triad.     

Charge-transfer states in strongly coupled phthalocyanine fullerene ensembles

Fluorescence and transient absorption measurements show that in strongly coupled ZnPc-C60 and H2Pc-C60 dyads charge-separated states are formed; large -delta GCR degree and small lambda assist in stabilising ZnPc(.+)-C60.-/H2Pc(.+)-C60.-.     

Formation of a long-lived charge-separated state of a zinc phthalocyanine-perylenediimide dyad by complexation with magnesium ion

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+.     

Photophysical and theoretical insights on non-covalently linked fullerene-zinc phthalocyanine complexes

The photo-physical aspects of non-covalently linked assemblies of a series of fullerenes, namely, C60, C70, tert-butyl-(1,2-methanofullerene)-61-carboxylate (1) and [6,6]-phenyl C70 butyric acid methyl ester (2) with a designed zinc phthalocyanine (ZnPc), viz., zinc-1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (3) in toluene medium are studied employing absorption spectrophotometric, steady state and time resolved fluorescence spectroscopic measurements. Of central interest in these investigations is the preferential binding of various fullerenes with ZnPc in toluene. The ground state interaction between fullerenes and 3 is first evidenced from UV-Vis measurements. Steady state fluorescence experiment reveals efficient quenching of the excited singlet state of 3 in presence of both underivatized and derivatized fullerenes. K values for the complexes of C60, C70, 1 and 2 with 3 are determined to be 6500, 22,230, 47,800 and 54,770 dm3 mol(-1), respectively. The magnitude of K suggests that 3 preferentially binds C70 and derivatized C70 in comparison to C60 and 1. Time resolved emission measurements establish that C(70)-3 and 2-3 complexes are stabilized much more in comparison to C(60)-3 and 1-3 systems in terms of charge separation process. Semi empirical calculations employing third parametric method substantiate the strong binding of C70 and its derivative with 3 in terms of heat of formation values of the respective complexes, and at the same time, determine the orientation of bound guest (here fullerenes) with the molecular plane of 3.     

Supramolecular Zinc Phthalocyanine–Imidazolyl Perylenediimide Dyad and Triad: Synthesis,Complexation, and Photophysical Studies

Two new supramolecular architectures based on zinc phthalocyanine (Pc) and imidazolyl‐substituted perylenediimide (PDI), ZnPc/DImPDI/ZnPc 1 and ZnPc/ImPDI 2 , have been prepared. A strong electron‐donor, 8 , which contained eight tert‐octylphenoxy groups was synthesized to ensure high solubility, thereby reducing aggregation in solution and providing σ‐donor features while avoiding regioisomeric mixtures. Also, PDI units were functionalized with tert‐octylphenoxy groups at the bay positions, which provide solubility to avoid aggregation in solution, together with one and two imidazole moieties in the amide position, 6 and 4 , respectively, to be able to strongly coordinate with the ZnPc complex. Supramolecular complexation studies by ¹H NMR spectroscopy and ESI‐MS demonstrate a high coordinative binding constant between imidazole‐substituted 4 or 6 and 8 . The same results were confirmed by UV/Vis and fluorescence titration studies. UV/Vis titration studies revealed the formation of a 1:1 complex ZnPc/ImPDI 2 for the systems 8 and 6 and a 2:1 complex ZnPc/DImPDI/ZnPc 1 for the interaction of 8 and 4 . The binding constant in both cases was determined to be on the order of 10⁵ M ⁻¹. Femtosecond laser flash photolysis measurements provided a direct proof of the charge‐separated state within both supramolecular assemblies by observing the transient absorption band at 820 nm due to the zinc phthalocyanine radical cation. The lifetimes of charge‐separated states are (9.8±3) ns for triad 1 and (3±1) ns for dyad 2 . As far as we know, this is the first time that a radical ion pair has been detected in a supramolecular assembled ZnPc–PDI system and has obtained the longest lifetime of a charge‐separated state published for ZnPc–PDI assemblies.     

New photophysical insights in noncovalent interaction between fulleropyrrolidine and a series of zincphthalocyanines

The present article reports, for the first time, the photophysical aspects of noncovalent interaction of a fullerene derivative, namely, C(60) pyrrolidine tris-acid ethyl ester (PyC(60)) with a series of zincphthalocyanines, for example, underivatized zincphthalocyanine (1), zinc-1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (2), and zinc-2,3,9,10,16,17,23,24-octakis-(octyloxy)-29H,31H-phthalocyanine (3) in toluene. Ground state electronic interaction of PyC(60) with 1, 2 and 3 has been evidenced from the observation of well-defined charge transfer (CT) absorption bands in the visible region. Utilizing the CT transition energy, vertical electron affinity (E(A)(v)) of PyC(60) is determined. Steady state fluorescence experiment enables us to determine the value of binding constant (K) in the magnitude of 2.60 × 10(4) dm(3)·mol(-1), 2.20 × 10(4) dm(3)·mol(-1), and 1.27 × 10(4) dm(3)·mol(-1) for the noncovalent complexes of PyC(60) with 1, 2, and 3, respectively. K values of PyC(60)-ZnPc complexes suggest that PyC(60) is incapable of discriminating between 1, 2, and 3 in solution. Lifetime experiment signifies the importance of static quenching phenomenon for our presently investigated supramolecules and it yields larger magnitude of charge separated rate constant for the PyC(60)-1 species in toluene. Photoinduced energy transfer between PyC(60) and ZnPc derivatives, namely, 1, 2, and 3, in toluene, has been evidenced with nanosecond laser photolysis method by observing the transient absorption bands in the visible region; transient absorption studies establish that energy transfer from (T)PyC(60)* to the ZnPc occurs predominantly, as confirmed by the consecutive appearance of the triplet states of PyC(60). Theoretical calculations at semiempirical level (PM3) evoke the single projection geometric structures for the PyC(60)-ZnPc systems in vacuo, which also proves that interaction between PyC(60) and ZnPc is governed by the electrostatic mechanism rather than dispersive forces associated with π-π interaction.     

Analysis and regulation of unusual adsorption of phthalocyanine zinc(II) into a Nafion film as investigated by UV-vis spectroscopic techniques

Phthalocyanine zinc(II) (ZnPc) was found to be adsorbed well into a Nafion (Nf) film. The kinetic analysis suggested that the adsorption of ZnPc into the Nf film is controlled by its diffusion in the Nf film with a diffusion coefficient of D = 1.9 x 10(-6) cm(2) s(-1) that is higher than those (10(-9)-10(-12) cm(2) s(-1)) of cationic redox molecules in the Nf film by 3-6 orders of magnitude. The adsorption isothermal was analyzed by a Brunauer-Emmett-Teller (BET) equation suggesting multilayer adsorption of ZnPc into the film. The BET analysis provided the amount of ZnPc for monolayer adsorption (w(m) = 1.50 x 10(-7) mol cm(-2)), from which the effective area for the ZnPc adsorption was estimated to be larger by a factor of 1.7 x 10(3) than the Nf film area (1.0 cm(2)). The absorption spectra of a Nf film adsorbing ZnPc ((Nf/ZnPc)(ads) film) exhibited two broad absorption bands at 385 and 680-750 nm without any structural features, which is significantly different from the absorption spectra of either ZnPc solution in DMF or a (Nf/ZnPc)(mix) film prepared from a DMF solution containing Nf and ZnPc by solvent evaporation. This is ascribed to the formation of a ZnPc aggregate in the (Nf/ZnPc)(ads) film. Photoluminescence data for the (Nf/ZnPc)(mix) film suggested the presence of a ZnPc monomer and dimer at equilibrium in the film with a concentration of 0.1 M and that energy transfer occurs from the monomer to the dimer in excitation of the monomer (at lambda(ex) = 609 nm) to yield emission from the dimer. By contrast, photoluminescence data for the (Nf/ZnPc)(ads) film suggested that the excited ZnPc is self-quenched significantly by the formation of the ZnPc aggregate in the film. The lesser electroactivity of ZnPc in the (Nf/ZnPc)(ads) film compared with that in the (Nf/ZnPc)(mix) film could be ascribable to more difficult diffusion of ZnPc in the former film due to the formation of the ZnPc aggregate. The adsorption of ZnPc into the Nf film was significantly regulated by simple pretreatments of the Nf film such as immersion in solvents and storage under solvent vapors. The regulation was explained by controlled physical and chemical properties of a channel for mass and ion transport that is formed by sulfonate groups, countercations, and solvent molecules in the Nf film.     

Photophysical properties of the ReI and RuII complexes of a new C60-substituted bipyridine ligand

The rhenium(I) and ruthenium(II) complexes of a fullerene-substituted bipyridine ligand have been prepared. Electrochemical studies indicate that some ground state electronic interaction between the fullerene subunit and the metal-complexed moiety are present in the Re(I) but not the Ru(II) complex. The photophysical properties have been investigated by steady-state and time-resolved UV/Vis-NIR luminescence spectroscopy and nanosecond laser flash photolysis in CH2Cl2 solution, and compared to those of the corresponding model compounds. Excitation of the methanofullerene moiety in the dyads does not lead to excited state intercomponent interactions. Instead, excitation of the metal-complexed unit shows that the lowest triplet metal-to-ligand-charge-transfer excited state ((3)MLCT) centered on the Re(I)- or Ru(II)-type unit is quenched with a rate constant of about 2.5 x 10(8) s(-1). The quenching is attributed to an electron-transfer (ElT) process leading to the reduction of the carbon sphere, as determined by luminescence spectroscopy for the Ru(II) dyad. Experimental detection of electron transfer in the Re(I) dyad is prevented due to the unfavorable absorption of the metal-complexed moiety relative to the fullerene unit. However, it can be postulated on the basis of energetic/kinetic arguments and by comparison with the Ru(II)-type array. The primary ElT process is followed by charge-recombination to give the lowest-lying fullerene triplet excited state (3C60) with quantitative yield, as determined by sensitized singlet oxygen luminescence experiments. Direct (3)MLCT-->3C60 triplet-triplet energy-transfer (EnT) does not successfully compete with ElT since it is highly exoergonic and located in the Marcus inverted region. The quantum yield of singlet oxygen sensitization (Phi(delta)) of the Re(I)-based dyad is found to be lower (0.80) than for the corresponding Ru(II) derivative (1.0). This is likely to be the consequence of different conformational structures for the two dyads, rather than a different yield of 3C60 formation.     

C60富勒烯-哌啶硫代荒酸酯稠合体的合成与三线态特征

C₆₀富勒烯与2-(哌啶-硫代荒酸酯)-1,3-丁二烯通过Diels-Alder环加成反应得到C₆₀富勒烯-哌啶硫代荒酸酯稠合体,运用现代波谱技术等确定了产物结构;用半经验方法PM3和AM1计算预测环加成反应性和C₆₀富勒烯-哌啶硫代荒酸酯稠合体的性能.激光光解时间分辨技术初步探究了单加成的C₆₀富勒烯-哌啶硫代荒酸酯稠合体(C₆₀-PX)三线态特征以及与四-(2-噻吩基)-四硫富瓦烯(TT-TTF)分子间的光诱导电子转移反应.     

Synthesis and photophysical properties of fullerene-phthalocyanine-porphyrin triads and pentads

The synthesis and photophysical properties of several fullerene-phthalocyanine-porphyrin triads (1-3) and pentads (4-6) are described. The three photoactive moieties were covalently connected in an one-step synthesis through 1,3-dipolar cycloaddition to C(60) of the corresponding azomethine ylides generated in situ by condensation reaction of a substituted N-porphyrinylmethylglycine derivative and an appropriated formyl phthalocyanine or a diformyl phthalocyanine derivative, respectively. ZnP-C(60)-ZnPc (3), (ZnP)(2)-ZnPc-(C(60))(2) (6), and (H(2)P)(2)-ZnPc-(C(60))(2) (5) give rise upon excitation of their ZnP or H(2)P components to a sequence of energy and charge-transfer reactions with, however, fundamentally different outcomes. With (ZnP)(2)-ZnPc-(C(60))(2) (6) the major pathway is an highly exothermic charge transfer to afford (ZnP)(ZnP(.+))-ZnPc-(C(60)(.-))(C(60)). The lower singlet excited state energy of H(2)P (i.e., ca. 0.2 eV) and likewise its more anodic oxidation (i.e., ca. 0.2 V) renders the direct charge transfer in (H(2)P)(2)-ZnPc-(C(60))(2) (5) not competitive. Instead, a transduction of singlet excited state energy prevails to form the ZnPc singlet excited state. This triggers then an intramolecular charge transfer reaction to form exclusively (H(2)P)(2)-ZnPc(.+)-(C(60)(.-))(C(60)). A similar sequence is found for ZnP-C(60)-ZnPc (3).     

Spectral, electrochemical, and photophysical studies of a magnesium porphyrin-fullerene dyad

A covalently linked magnesium porphyrin-fullerene (MgPo-C60) dyad was synthesized and its spectral, electrochemical, molecular orbital, and photophysical properties were investigated and the results were compared to the earlier reported zinc porphyrin-fullerene (ZnPo-C60) dyad. The ab initio B3LYP/3-21G(*) computed geometry and electronic structure of the dyad predicted that the HOMO and LUMO are mainly localized on the MgP and C60 units, respectively. In o-dichlorobenzene containing 0.1 M (n-Bu)4NClO4, the synthesized dyad exhibited six one-electron reversible redox reactions within the potential window of the solvent. The oxidation and reduction potentials of the MgP and C60 units indicate stabilization of the charge-separated state. The emission, monitored by both steady-state and time-resolved techniques, revealed efficient quenching of the singlet excited state of the MgP and C60 units. The quenching pathway of the singlet excited MgP moiety involved energy transfer to the appended C60 moiety, generating the singlet excited C60 moiety, from which subsequent charge-separation occurred. The charge recombination rates, k(CR), evaluated from nanosecond transient absorption studies, were found to be 2-3 orders of magnitude smaller than the charge separation rate, k(CS). In o-dichlorobenzene, the lifetime of the radical ion-pair, MgPo*+-C60*-, was found to be 520 ns which is longer than that of ZnPo*+-C60*- indicating better charge stabilization in MgPo-C60. Additional prolongation of the lifetime of MgPo*+-C60*- was achieved by coordinating nitrogenous axial ligands. The solvent effect in controlling the rates of forward and reverse electron transfer is also investigated.     

Supramolecular pattern of fullerene on 2D bimolecular "chessboard" consisting of bottom-up assembly of porphyrin and phthalocyanine molecules

Two-component adlayers consisting of zinc(II) phthalocyanine (ZnPc) and a metalloporphyrin, such as zinc(II) octaethylporphyrin (ZnOEP) or zinc(II) tetraphenylporphyrin (ZnTPP), were prepared by immersing either an Au(111) or Au(100) substrate in a benzene solution containing those molecules. The bimolecular adlayers thus prepared were investigated in 0.1 M HClO4 by cyclic voltammetry (CV) and electrochemical scanning tunneling microscopy (EC-STM). A supramolecularly organized "chessboard" structure was formed for the ZnPc and ZnOEP bimolecular array on Au(111), while characteristic nanohexagons were found in the ZnTPP and ZnOEP bimolecular adlayer. EC-STM revealed that the surface mobility and the molecular re-organization of ZnPc and ZnOEP on Au(111) were tunable by manipulating the electrode potential, whereas the ZnTPP and ZnOEP bimolecular array was independent of the electrode potential. A "bottom-up" hybrid assembly of fullerene molecules was formed successfully on an alternate array of bimolecular ZnPc and ZnOEP molecules. The bimolecular "chessboard" served as a template to form the supramolecular assembly of C60 by selective trapping in the open spaces. A supramolecular organization of ZnPc and ZnOEP was also found on the reconstructed Au(100)-(hex) surface. A highly ordered, compositionally disordered but alternate array of ZnPc and ZnOEP was formed on the reconstructed Au(100)-(hex) surface, indicating that the bimolecular adlayer structure is dependent on the atomic arrangement of underlying Au in the formation of supramolecular nanostructures composed of those molecules. On the bimolecular array consisting of ZnPc and ZnOEP on the Au(100)-(hex), no highly ordered supramolecular assembly of C60 was found, suggesting that the supramolecular assembly of C60 molecules is strongly dependent upon the bimolecular packing arrangement of ZnPc and ZnOEP.     

Solid film versus solution-phase charge-recombination dynamics of exTTF-bridge-C60 dyads

The charge-recombination dynamics of two exTTF-C60 dyads (exTTF = 9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene), observed after photoinduced charge separation, are compared in solution and in the solid state. The dyads differ only in the degree of conjugation of the bridge between the donor (exTTF) and the acceptor (C60) moieties. In solution, photoexcitation of the nonconjugated dyad C60-BN-exTTF (1) (BN = 1,1'-binaphthyl) shows slower charge-recombination dynamics compared with the conjugated dyad C60-TVB-exTTF (2) (TVB = bisthienylvinylenebenzene) (lifetimes of 24 and 0.6 micros, respectively), consistent with the expected stronger electronic coupling in the conjugated dyad. However, in solid films, the dynamics are remarkably different, with dyad 2 showing slower recombination dynamics than 1. For dyad 1, recombination dynamics for the solid films are observed to be tenfold faster than in solution, with this acceleration attributed to enhanced electronic coupling between the geminate radical pair in the solid film. In contrast, for dyad 2, the recombination dynamics in the solid film exhibit a lifetime of 7 micros, tenfold slower than that observed for this dyad in solution. These slow recombination dynamics are assigned to the dissociation of the initially formed geminate radical pair to free carriers. Subsequent trapping of the free carriers at film defects results in the observed slow recombination dynamics. It is thus apparent that consideration of solution-phase recombination data is of only limited value in predicting the solid-film behaviour. These results are discussed with reference to the development of organic solar cells based upon molecular donor-acceptor structures.     

GW/BSE Nonadiabatic Dynamics Simulations on Excited-State Relaxation Processes of Zinc Phthalocyanine-Fullerene Dyads: Roles of Bridging Chemical Bonds

In this work, we employ electronic structure calculations and nonadiabatic dynamics simulations based on many-body Green function and Bethe-Salpeter equation (GW/BSE) methods to study excited-state properties of a zinc phthalocyanine-fullerene (ZnPc-C\begin{document}$ _{60} $\end{document}) dyad with 6-6 and 5-6 configurations. In the former, the initially populated locally excited (LE) state of ZnPc is the lowest S\begin{document}$ _1 $\end{document} state and thus, its subsequent charge separation is relatively slow. In contrast, in the latter, the S\begin{document}$ _1 $\end{document} state is the LE state of C\begin{document}$ _{60} $\end{document} while the LE state of ZnPc is much higher in energy. There also exist several charge-transfer (CT) states between the LE states of ZnPc and C\begin{document}$ _{60} $\end{document}. Thus, one can see apparent charge separation dynamics during excited-state relaxation dynamics from the LE state of ZnPc to that of C\begin{document}$ _{60} $\end{document}. These points are verified in dynamics simulations. In the first 200 fs, there is a rapid excitation energy transfer from ZnPc to C\begin{document}$ _{60} $\end{document}, followed by an ultrafast charge separation to form a CT intermediate state. This process is mainly driven by hole transfer from C\begin{document}$ _{60} $\end{document} to ZnPc. The present work demonstrates that different bonding patterns (i.e. 5-6 and 6-6) of the C\begin{document}$ - $\end{document}N linker can be used to tune excited-state properties and thereto optoelectronic properties of covalently bonded ZnPc-C\begin{document}$ _{60} $\end{document} dyads. Methodologically, it is proven that combined GW/BSE nonadiabatic dynamics method is a practical and reliable tool for exploring photoinduced dynamics of nonperiodic dyads, organometallic molecules, quantum dots, nanoclusters, etc.     

Effect of dual fullerenes on lifetimes of charge-separated States of subphthalocyanine-triphenylamine-fullerene molecular systems

Photoinduced intramolecular electron-transfer events of the newly synthesized subphthalocyanine-triphenylamine-fullerene triad (SubPc-TPA-C60) and subphthalocyanine-triphenylamine-bisfullerene tetrad (SubPc-TPA-(C(60))(2)) were studied. The geometric and electronic structures of the triad were probed by ab initio B3LYP/3-21G method, which predicts SubPc-TPA(*+)-C(60)(*-) as a stable charge-separated state. The photoinduced events via the excited singlet state of SubPc were monitored by time-resolved emission measurements as well as transient absorption techniques. Efficient charge-separations via the excited states of SubPc were observed with the rates of approximately 10(10) s(-)1. Compared with the SubPc-TPA dyad, a long-lived charge-separated state was observed for the SubPc-TPA-C(60) triad with the lifetime of the radical ion pairs (tau(RIP)) of 670 ns in benzonitrile. Interestingly, further charge stabilization was achieved in the charge-separated state of SubPc-TPA-(C(60))(2), in which the tau(RIP) was found to be 1050 ns in benzonitrile.