Article pubs.acs.org/JPCC
Photophysical Processes Occurring in a Zn-phthalocyanine in Ethanol Solution and on TiO2 Nanostructures Alessandro Iagatti,†,‡ Sandra Doria,†,‡ Agnese Marcelli,† Nicola Angelini,§ Sara Notarantonio,§ Anna Maria Paoletti,§ Giovanna Pennesi,§ Gentilina Rossi,§ Gloria Zanotti,§ Giuseppe Calogero,∥ and Paolo Foggi*,†,‡,⊥ †
European Laboratory for Non Linear Spectroscopy (LENS), Università di Firenze, via Nello Carrara 1, 50019 Sesto Fiorentino, Florence, Italy ‡ INO−CNR, Istituto Nazionale di Ottica − Consiglio Nazionale delle Ricerche, Largo Fermi 6, 50125 Florence, Italy § CNR, Istituto Struttura della Materia, Via Salaria Km. 29.5, 00015 Monterotondo Stazione, Roma, Italy ∥ CNR, Istituto per i Processi Chimico-Fisici, Via F. Stagno D’Alcontres 37, 98158 Messina, Italy ⊥ Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy S Supporting Information *
ABSTRACT: The photophysics of 9(19),16(17),23(24)-tri-tert-butyl-2[ethynyl-(4-carboxymethyl)phenyl] phthalocyaninatozinc(II) (ZnPc) in solution and adsorbed on TiO2 and ZrO2 nanoparticle films is characterized by stationary and time-resolved spectroscopies in the subpicosecond to nanosecond time interval. The comparison between the solution and the solid substrate data allows us to identify different pathways of the energy and electron relaxation. On the solid substrate, the presence of H-aggregates adds a further nonradiative deactivation channel competing with the charge injection into the TiO2-conducting band, thus providing an explanation of the reduced efficiency of the charge transfer processes. The comparison between the kinetics recorded after excitation of the S0−S2 transition and those recorded after excitation of the S0−S1 transition provides an estimate of the internal conversion between S2 and S1 which occurs very efficiently and on an ultrafast (
