The effect of aggregation on the nonlinear optical absorption performance of indium and gallium phthalocyanines in a solution and co-polymer host Sezen Tekin a , H. Gul Yaglioglu a, * , Ayhan Elmali a , Ulas ¸ Kürüm a , Hülya Yanık b , Duygu Aydın Tekdas ¸ b , Mahmut Durmus ¸ b, ** , Vefa Ahsen b a Department of Engineering Physics, Faculty of Engineering, Ankara University, 06100 Bes ¸evler, Ankara, Turkey b Gebze Institute of Technology, Department of Chemistry, P.O.Box:141, Gebze 41400, Kocaeli, Turkey highlights graphical abstract < The effect of aggregation on the nonlinear absorption and the excited state lifetimes were studied. < UVeVis absorption spectra revealed that organization of investigated molecules in PMMA films show H-aggregation. < Fast transitions (intermolecular energy transfers) in PMMA films were observed. < Intermolecular energy transfer due to aggregation reduces transition to triplet levels. < Aggregation reduces RSA signal observed in OA Z-scan experiments for the samples in a host PMMA polymer matrix. article info Article history: Received 9 July 2012 Received in revised form 5 November 2012 Accepted 18 November 2012 Keywords: Optical materials Thin films Coatings Optical properties abstract The nonlinear optical properties (NLO) of Pcs can be modified by substituting different metal atoms into the ring or altering peripheral and axial functionalities. In this study, nonlinear optical absorption properties of tetra-substituted gallium and indium phthalocyanine complexes both in solution and polymeric film have been investigated by open aperture Z-scan measurements with nanosecond pulses at 532 nm. All investigated compounds exhibited reverse saturable absorption for both solution and film experiments. The investigated compounds in the solution showed better nonlinear optical absorption properties than polymeric films. The observed nonlinear optical absorption differences depending on the aggregation are discussed using the ultrafast dynamics and decay processes of excited states found from femtosecond pump-probe spectroscopy with white light continuum experiments. Ó 2012 Elsevier B.V. All rights reserved. 1. Introduction Metallophthalocyanines (MPcs) show fast, large and reversible nonlinear optical absorption which is based on reverse saturable absorption (RSA) [1,2]. Chemical modifications of Pcs like axial substitution at the central metal atom or peripheral substitution on the Pc macrocycle make it possible to reduce the intermolecular * Corresponding author. Tel.: þ90 312 2033507; fax: þ90 312 2127343. ** Corresponding author. Tel.: þ90 262 6053108; fax: þ90 262 6053101. E-mail addresses: yoglu@eng.ankara.edu.tr (H.G. Yaglioglu), durmus@gyte.edu.tr (M. Durmus ¸ ). Contents lists available at SciVerse ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys 0254-0584/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.matchemphys.2012.11.056 Materials Chemistry and Physics 138 (2013) 270e276