The vibronic fine structure of the emission spectrum of silicon phthalocyanine

Abstract

Sharp line emission spectra of the silicon phthalocyanine complex ((n- C 6 H 13)3 SiO )2 SiPc at low temperatures are resolved in multiple sites, and the vibronic fine structure of single-site emissions is identified. DFT methods are used to calculate the complete set of normal modes of the Cl 2 SiPc analogue. Geometry optimization of the excited state further yields the Franck–Condon and Jahn–Teller distortions in the emitting state. These results are combined to obtain theoretical Huang–Rhys factors for the active modes, which compare favourably with the experimental spectrum. The dominant satellites are a 675 cm−1 mode, which is identified as a totally symmetric bending of the four pyrrole rings, and a 1552 cm−1 mode, which is assigned to an antisymmetric stretching of the aza-nitrogens with tetragonal b 1 g symmetry.