Optical Limiting Mechanisms in a Neat Liquid Phthalocyanine Thin Film

Abstract

This paper describes some of the novel physical, photophysical, and optical properties of a new material, lead tetrakis-(β-ethyl-terminated-polyethyleneoxide)phthalocyanine (PbPc(β-PEO)4). These novel properties were achieved by molecular engineering of the long polyethylene oxide (PEO) side chains. In the material described here, the PEO side chains are O(CH2CH2O)nCH2CH3 and have an average molecular weight of 350 implying that n=7. PbPc(β-PEO)4 is a viscous liquid in the pure form. It readily forms thin films of high optical quality by capillary action. By comparison, the usual unsubstituted phthalocyanine forms polycrystalline thin films that sublime only at temperatures above 400C. The feature of this material most important to our group is that this neat liquid maintains many of the photophysical properties of the phthalocyanine electronic system. Here we emphasize the physical properties that are useful for optical limiting applications.