Photophysical Processes Occurring in a Zn-phthalocyanine in Ethanol Solution and on TiO2 Nanostructures

Year: 2015

Authors: Iagatti A., Doria S., Marcelli A., Angelini N., Notarantonio S., Paoletti A.M., Pennesi G., Rossi G., Zanotti G., Calogero G., Foggi P.

Autors Affiliation: European Laboratory for Non Linear Spectroscopy (LENS), Università di Firenze, via Nello Carrara 1, Sesto Fiorentino, Florence 50019, Italy; INO-CNR, Istituto Nazionale di Ottica – Consiglio Nazionale delle Ricerche, Largo Fermi 6, Florence, 50125, Italy; CNR, Istituto Struttura della Materia, Via Salaria Km. 29.5, Monterotondo StazioneRoma 00015, Italy; CNR, Istituto per i Processi Chimico-Fisici, Via F. Stagno D’Alcontres 37, Messina, 98158, Italy; Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Via Elce di Sotto 8, Perugia, 06123, Italy

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 Ti-2-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 S-0-S-2 transition and those recorded after excitation of the S-0-S-1 transition provides an estimate of the internal conversion between S-2 and S-1 which occurs very efficiently and on an ultrafast (<50 fs) time scale. The ground-state recovery characterized by the decay of the bleaching band in the transient spectra slows down in TiO2 samples and is taken as evidence of the charge injection in this kind of sample. Journal/Review: JOURNAL OF PHYSICAL CHEMISTRY C

Volume: 119 (35)      Pages from: 20256  to: 20264

KeyWords: Charge transfer; Laser spectroscopy, Charge transfer process; Electron relaxation; Ground state recovery; Internal conversions; Non-radiative deactivation; Photophysical process; Time-resolved spectroscopy; Zn phthalocyanines, Ground state
DOI: 10.1021/acs.jpcc.5b04978

Citations: 9
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