Matteo M. Salamone

Panchromatic squaraine compounds for broad band light harvesting electronic devices

Squaraine compounds are currently investigated as high performance active components in both organic and hybrid photovoltaic devices as well as in photodetectors. Their most valuable features include a particularly efficient optical absorption in the Vis-NIR region, high polarizability, and a remarkable chemical stability. Their full exploitation is somewhat limited by a negligible absorption in the UV-Vis region (prototypical squaraines basically do not absorb below 500 nm). The aim of the present paper is the design and synthesis of truly panchromatic squaraines to be effectively employed as the photoactive materials in Vis operating optoelectronic devices. Our strategy involves the design of squaraines that are both nonsymmetric and core-substituted with suitable electron-withdrawing groups. We show the effect of such a design strategy by means of UV-Vis spectroscopy, cyclic voltammetry and prototypical device performances rationalization.

Gray to Colorless Switching, Crosslinked Electrochromic Polymers with Outstanding Stability and Transmissivity From Naphthalenediimmide‐Functionalized EDOT

The design, synthesis, polymerization and full electrochemical and spectroelectrochemical characterization of a new naphtalendiimide-functionalized PEDOT cross-linked electrochromic material is reported. The polymer shows exceptionally high redox reversibility, almost complete colorlessness in the bleached state and a gray color in the reduced state.

Thiocyanate-free cyclometalated ruthenium sensitizers for solar cells based on heteroaromatic-substituted 2-arylpyridines

The first examples of thiocyanate-free thiophene-substituted Ru(II) cyclometalated complexes, based on thiophene-derived 2-(2,4-difluorophenyl)pyridine ligands, are presented and investigated as photosensitizers in DSCs. Upon thiophene substitution the complexes presented enhanced optical properties compared to the reference dye with no thiophene substitution. DSCs based on the dithienyl-derived dye showed power conversion efficiencies up to 5.7%, more than twice that containing the complex without the thiophene substitution.

Exomethylene-3,4-ethylenedioxythiophene (emEDOT): A New Versatile Building Block for Functionalized Electropolymerized Poly(3,4-ethylenedioxythiophenes) (PEDOTs)

A new versatile thiophene derivative exomethylene-3,4-ethylenedioxythiophene (emEDOT) is introduced. The molecule can be straightforwardly prepared in two steps from commercially available derivatives and enables facile further derivatization through both acid catalyzed additions of alcohols and standard thiol-ene click chemistry. The preparation of electrochromic materials and of an electrochemical avidine sensor is shown by the oxidative polymerizations of several functionalized EDOT monomers straightforwardly prepared from emEDOT.

Enhanced photocatalytic hydrogen generation using carbazole-based sensitizers

Phenothiazine-, phenoxazine- and carbazole-based dyes have been synthesized and used as photosensitizers in Pt/TiO2 films for photocatalytic hydrogen generation. Compared to commonly used phenothiazine dyes, planar and sulphur-free carbazole derivatives showed different molecular and supramolecular features which in turn yielded greatly enhanced (one order of magnitude) H2 production performances.

An Integrated Theoretical/Experimental Study of Quinolinic–Isoquinolinic Derivatives Acting as Reversible Electrochromes

A series of compounds, featuring an ethenylic bridge and quinoline and isoquinoline end capping units possessing systematically varied substitution patterns, were prepared as molecular materials for electrochromic applications. The different structures were optimized in order to maximize the electrochromic contrast in the visible region, mostly by achieving a completely UV-absorbing oxidized state. Density functional theory (DFT) calculations are exploited in order to rationalize the correlation between the molecular structure, the functional groups’ electronic properties, and the electrochemical behavior. It is shown that the molecular planarity (i.e. ring/ring π conjugation) plays a major role in defining the mechanism of the electrochemical charge transfer reaction, while the substituent’s nature has an influence on the LUMO energy. Among the compounds here studied, the (E)-10-methyl-9-(2-(2-methylisoquinolinium-1-yl)-vinyl)-1,2,3,4-tetrahydroacri-dinium trifluoromethanesulfonate derivative shows the most interesting properties as an electrochromophore.