A soluble phthalocyanine derivative, tetra-α-(2-ethylbutoxyl)chloro-indium phthalocyanine, has been synthesized through the corresponding metal-free phthalocyanine. The optical limiting properties of its THF solution were investigated by a 7 ns pulses laser at 532 nm. It was found that the compound exhibited good optical limiting performance. With a very low input fluence, the output fluence roughly obeyed Beer's law, and the transmittance decreased very quickly with the increase of the input fluence. The optical limiting properties were attributed to its reverse saturable absorption. The transient absorption spectra and the triplet lifetime in the Argon saturated THF solution of the compound were measured by an ns laser-flash photolysis apparatus. The remarkably low tendency to aggregation and good solubility make it candidate worthy of further studies for potential application in optical limiting materials.

Key words: chloro-indium phthalocyanine, optical limiting, T-T absorption, reverse saturable absorption