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 C60 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‐C60‐ZnPc (3), (ZnP)2‐ZnPc‐(C60)2 (6), and (H2P)2‐ZnPc‐(C60)2 (5) give rise upon excitation of their ZnP or H2P components to a sequence of energy and charge‐transfer reactions with, however, fundamentally different outcomes. With (ZnP)2‐ZnPc‐(C60)2 (6) the major pathway is an highly exothermic charge transfer to afford (ZnP)(ZnP.+)‐ZnPc‐(C60.−)(C60). The lower singlet excited state energy of H2P (i.e., ca. 0.2 eV) and likewise its more anodic oxidation (i.e., ca. 0.2 V) renders the direct charge transfer in (H2P)2‐ZnPc‐(C60)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 (H2P)2‐ZnPc.+‐(C60.−)(C60). A similar sequence is found for ZnP‐C60‐ZnPc (3).
Photoactive fullerenes: Several fullerene–phthalocyanine–porphyrin triads and pentads, covalently connected, give rise upon excitation of their porphyrin components to a sequence of energy and charge‐transfer reactions.
Let it shine! The impact of the anchoring group on photovoltaic performance by a series of phthalocyanine sensitisers (see figure) has been demonstrated.
A series of unsymmetrical zinc ...phthalocyanines bearing an anchoring carboxylic function linked to the phthalocyanine ring through different spacers were designed for dye‐sensitised solar cells (DSSC). The modification of the spacer group allows not only a variable distance between the dye and the nanocrystalline TiO2, but also a distinct orientation of the phthalocyanine on the semiconductor surface. The photovoltaic data show that the nature of the spacer group plays a significant role in the electron injection from the photo‐excited dye into the nanocrystalline TiO2 semiconductor, the recombination rates and the efficiency of the cells. The incident monochromatic photon‐to‐current conversion efficiency (IPCE) for phthalocyanines bearing an insulating spacer is as low as 9 %, whereas for those with a conducting spacer an outstanding IPCE 80 % was obtained.
Let it shine! The impact of the anchoring group on photovoltaic performance by a series of phthalocyanine sensitisers (see figure) has been demonstrated.
Several zinc-based phthalocyanines have been synthesized and used in Dye-Sensitized Solar Cells (DSSC). The results have been compared with the standard TT1 phthalocyanine, which shows good ...light-to-energy conversion efficiencies in comparison with other IR sensitizers used in DSSC. We show herein that the anchoring moiety is critical for both achieving high injection yields and slow back electron transfer dynamics that affect the overall device efficiency. Moreover, based on these results, we have synthesized a new phthalocyanine with a superior performance, when compared to the TT1 dye, with a subtle change on the anchoring moiety, thus leading to a higher photocurrent response.
A novel covalently linked bis(60fullerene)−phthalocyanine triad is reported, exhibiting long-lived photoinduced charge separation both in solution and in the solid state. The first demonstration of a ...working solar cell using triad 1 as the active material is also presented.
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., ∼1012 s-1) and ultraslow charge recombination (i.e., ∼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 (∼3 ns), an impressive stabilization of 6 orders of magnitude.
A thorough investigation on the physicochemical properties, including electrochemisty and photophysics, of a new class of donor−acceptor hybrids, namely, phthalocyanine-fullerene dyads, consisting of ...free base 1a and zinc and copper complexes 1b and 1c, respectively, brings new insights into the stabilization of charge-separated radical ion pairs and the impact of redoxactive transition-metal centers on the photoperformance of macrocyclic phthalocyanines. In these dyads, the role of the phthalocyanines is twofold: First, it functions as an antenna (i.e., absorbing very efficiently light in the visible region of the solar spectrum) and, second, as a donor moleculeonce photoexcited. The initial photoexcitation is succeeded by an ultrafast electron transfer largely due to the strong electronic coupling between electron donor (Pc) and electron acceptor (C60) generating surprisingly long-lived radical ion pairs Pc•+−C60 •- with lifetimes of several nanoseconds. Large driving forces for the charge recombination and small reorganization energies of the Pc−C60 ensembles corroborate slow charge recombination dynamics, which, in turn, helps to rationalize the long lifetimes of Pc•+−C60 •-.
Alkynyl‐linked metallophthalocyanine dyads (see space‐filling model) can be readily prepared from appropriately functionalized unsymmetrical ethynyl‐phthalocyanines by means of metal‐mediated ...coupling. This method can be advantageously applied to the synthesis of push–pull substituted dimers and heterodimetallic systems. The influence of the central transition metals and substituents in the electronic spectra is discussed. These dimers with extended conjugation provide interesting targets for the investigation of their nonlinear optical properties.
Phthalocyanines linked to C60 have been synthesized by two general strategies. One of them involves the addition of an azomethine ylide prepared in situ from a formyl phthalocyanine to C60, and the ...other one involves a statistical condensation of two substituted phthalonitriles, one of them bearing the C60 moiety covalently attached. These new phthalocyanine‐fullerene dyads have been studied by cyclic voltammetry and Osteryoung square wave voltammetry, and inter‐ and intramolecular electronic interactions between the two electroactive subunits have been demonstrated.
Se han sintetizado ftalocianinas unidas a C60 siguiendo dos estrategias generales. Una de ellas implica la adición de un iluro de azometino preparado in situ a partir de la correspondiente formilftalocianina, y la otra utiliza la condensación estadística de dos ftalonitrilos sustituidos, uno de los cuales está unido covalentemente a la unidad de C60. Estas nuevas diadas de ftalocianina‐fullereno se han estudiado por voltametría cíclica y voltametría de onda cuadrada de Osteryoung, habiéndose puesto de manifiesto la existencia entre ambas subunidades electroactivas de interacciones electrónicas, inter‐ e intramoleculares.
