A series of homoleptic ([Tb(III)(Pc)(2) ]) and heteroleptic ([Tb(III)(Pc)(Pc')]) Tb(III) bis(phthalocyaninate) complexes that contain different peripheral substitution patterns (i.e., tert-butyl or tert-butylphenoxy groups) have been synthesized in their neutral radical forms and then reduced into their corresponding anionic forms as stable tetramethylammonium/tetrabutylammonium salts. All of these compounds were spectroscopically characterized and their magnetic susceptibility properties were investigated. As a general trend, the radical forms exhibited larger energy barriers for spin reversal than their corresponding reduced compounds. Remarkably, heteroleptic complexes that contain electron-donor moieties on one of the two Pc ligands show higher effective barriers and blocking temperatures than their homoleptic derivatives. This result is assigned to the elongation of the N-Tb distances in the substituted macrocycle, which brings the terbium(III) ion closer to the unsubstituted Pc, thus enhancing the ligand-field effect. In particular, heteroleptic [Tb(III) (Pc)(Pc')] complex 4, which contains one octa(tert-butylphenoxy)-substituted Pc ring and one bare Pc ring, exhibits the highest effective barrier and blocking temperature for a single-molecule magnet reported to date.

Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in: El acceso a la versión del editor puede requerir la suscripción del recurso Access to the published version may require subscription COMMUNICATION Combining novel electron-accepting phthalocyanines and nanorod-like CuO electrodes for p-type dye-sensitized solar cellsOliver Langmar, [a] Carolina R. Ganivet, [b] Annkatrin Lennert, [a] Rubén D. Costa, [a] Gema de la Torre, [b] Tomás Torres, [b] and Dirk M. Guldi [a] Abstract: In the current work, a novel route for the synthesis of two electron-accepting phthalocyanines featuring linkers with different length as sensitizers for p-type dye-sensitized solar cells are reported. Importantly, our devices -based on novel nanorod-like CuO photocathodes -feature efficiencies of 0.191%, which are to date the highest values ever reported for CuO-based DSSCs.

The use of Metal-Organic Frameworks as crystalline matrices for the synthesis of multiple component or multivariate solids by the combination of different linkers into a single material has emerged as a versatile route to tailor the properties of single component phases or even access new functions. This approach is particularly relevant for Zr6-MOFs due to the synthetic flexibility of this inorganic node. However, the majority of materials is isolated as polycrystalline solids, which are not ideal to decipher the spatial arrangement of parent and exchanged linkers for the formation of homogeneous structures or heterogeneous domains across the solid. Here we use High-Throughput methodologies to optimize the synthesis of single crystals of UiO-68 and UiO-68-TZDC, a photoactive analogue based on a tetrazine dicarboxylic derivative. The analysis of the single linker phases reveals the necessity of combining both linkers to produce multivariate frameworks that combine efficient light sensitization, chemical stability and porosity, all relevant to photocatalysis. We use solvent assisted linker exchange reactions to produce a family of UiO-68-TZDC% binary frameworks, which respect the integrity and morphology of the original crystals. Our results suggest that the concentration of TZDC in solution controls the distribution of this linker in the sibling crystals for a random mixture or the formation of core-shell domains. We also demonstrate how the possibility of generating an asymmetric distribution of both linkers has a negligible effect on the electronic structure and optical bandgap of the solids but controls their performance for drastic changes in the photocatalytic activity towards proton or methyl viologen reduction.

aWe introduce a novel and comprehensive approach for the evaluation and interpretation of electrochemical impedance spectroscopy (EIS) measurements in p-type DSSCs. In detail, we correlate both the device performance and EIS figures-of-merit of a series of devices in which, the calcination temperature, film thickness, and electrolyte concentration have been systematically modified. This new approach enables the separation of the different processes across the dye/semiconductor/electrolyte interface, namely the unfavorable charge recombination and the favorable electron injection/regeneration processes. In addition, studies on non-sensitized CuO and NiO electrodes provide insights into their affinity towards a reaction with the electrolyte -CuO is far less reactive towards the polyiodide species. Overall, this work underlines the superior features of CuO with respect to NiO for p-DSSCs and demonstrates a comprehensive optimization of the CuO-based DSSCs with respect to the device architecture by the aid of EIS analysis.

Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in: El acceso a la versión del editor puede requerir la suscripción del recurso Access to the published version may require subscription COMMUNICATION Combining novel electron-accepting phthalocyanines and nanorod-like CuO electrodes for p-type dye-sensitized solar cellsOliver Langmar, [a] Carolina R. Ganivet, [b] Annkatrin Lennert, [a] Rubén D. Costa, [a] Gema de la Torre, [b] Tomás Torres, [b] and Dirk M. Guldi [a] Abstract: In the current work, a novel route for the synthesis of two electron-accepting phthalocyanines featuring linkers with different length as sensitizers for p-type dye-sensitized solar cells are reported. Importantly, our devices -based on novel nanorod-like CuO photocathodes -feature efficiencies of 0.191%, which are to date the highest values ever reported for CuO-based DSSCs.Current developments in p-type DSSCs focuses on exploring novel electrodes and electron acceptors. [1,2] Concerning the former, the most prominent material has been nickel(II) oxide (NiO), despite drawbacks such as low transparency, electrode thickness, and low conductivity. [2] To tackle some of the aforementioned bottlenecks, the preparation of binary NiXO semiconductors, where X is cobalt, have recently evolved as a powerful approach.[3] A viable alternative is based on the long overlooked copper(II) oxide (CuO), whose films feature higher conductivity, better charge carrier mobility, and comparable valence band energy relative to NiO films. [4,5] Still, the most recent report on CuO based p-type DSSCs is dated from 2008.[6] Very likely, state-of-the-art efficiencies as low as 0.011% resulted in a moderate interest. Recent improvements in the field of CuO based p-type DSSCs are due to the use of copper delafossite (CuXO2) electrodes with X being aluminum, chromium, or gallium.[ [8] perylenediimides, [9] perylene-bithiophene-triphenylamine triads, [10] porphycenes, [11] and ruthenium complexes, [12] have been designed and probed. Notably, porphyrinoids have led to the most efficient n-type DSSCs up to date. [13,14] Key merits of porphyrins, and specially of their synthetic related phthalocyanines , (Pcs), [15,16] are their exceptional light-harvesting features and their facile functionalization with either electrondonors or electron-acceptors, underlining their potential for DSSCs. In light of the latter, tuning the physicochemical features of phthalocyanines towards new electron-accepting dyes [17,18] by means of placing electron-withdrawing substituents at their periphery, complements, in the current work, our research regarding nanorod-like CuO electrodes. ; ii) IBX, DMSO/THF; iii) H3NSO3/H2O followed by NaClO2; iv) propargyl alcohol, Pd(PPh3)2Cl2, CuI, NEt3, THF Notably, the synergy of nanorod-like CuO DSSCs and electronaccepting Pcs enables the construction of p-DSSCs with efficiencies as high as 0.103% and 0.191% with iodine-and cobalt-based electrolytes, respectively. The latter represents...