Dynamic effects in materials designed for optical limiting

Summary form only given. Two critical photophysical properties affect materials designed for application as optical limiters based on reverse saturable absorption: 1) The excited state absorption cross section must exceed that of the ground state, and 2) population of the excited state must persist sufficiently long to be effective against the incident optical beam. Peripherally substituted phthalocyanines typically exhibit a large region of the visible spectrum where the first condition is met. However, their excited state lifetimes vary greatly with central metal, peripheral substituent, and material morphology. Further, concentration and excitation intensity can influence the excited state dynamics. This paper examines the dynamics exhibited by thin films of materials made from a series of metal-free and lead phthalocyanines, concentrating on the material properties that influence the excited state response. Characterization and control of these properties can lead to improved optical limiters.