Large redshift in absorption spectra of titanylphthalocyanine thin films

Abstract

Titanylphthalocyanine is deposited onto sapphire by organic molecular beam deposition to grow films of 2.5 to 100 nm. The first layer grown on the sapphire surface is not phase II; however, phase II grows on the first layer. The first layer is annealed and changed to phase II during deposition. The Q-band of phase II shows a large redshift. Calculations using molecular exciton theory show that molecular columns grow in two directions parallel to the substrate surface. Each of these columns has a favorable molecular arrangement for a large redshift, such as J-aggregates. The film thickness has a low dependence on the redshift, a result which is consistent with the calculation results. © 1995 The Japan Society of Applied Physics.