Poly methyl methacrylate films containing metallophthalocyanines in the presence of CdTe quantum dots: Non-linear optical behaviour and triplet state lifetimes

Abstract

Non-linear optical (NLO) parameters were determined for phthalocyanine complexes containing In, Ga and Zn as central metals when embedded in poly (methyl methacrylate) polymer in the absence and presence of quantum dots (QDs) in an effort to create the most optimal optical limiting material. The QDs employed were CdTe-TGA (TGA = thioglylcolic acid). Triplet lifetimes generally increased as the value of the ratio of absorption cross sections of the excited state to that of the ground state (k) decreased on addition of CdTe-TGA to the phthalocyanines. The saturation energy density (F-sat) values were generally smaller in the films when compared to the solutions. F-sat, I-lim, Im[chi((3))]/alpha and gamma all gave values which were of optimal range (i.e. the Im[chi((3))]/alpha and gamma values were high enough to ensure adequate optical limiting but not too high to make the compounds behave like optical filters. Also, the F-sat and I-lim values were small enough to mean that the optical limiting process started at an intensity which was not too high) for complex 10 containing Zn central metal and tetrasubstituted with amino groups. (C) 2013 Elsevier B.V. All rights reserved.