The temperature dependence of photoluminescence and absorption spectra of MPc (M = Zn, Co, Mg, Cu) thin films

In this paper, photoluminescence (PL), transmittance (T) and absorption (A) measurements have been performed for the first time on metallophthalocyanines (MPc; M = Zn, Co, Mg, Cu) thin layers grown by quasi molecular beam evaporation on quartz substrates. Investigated films of ZnPc and MgPc show PL emission from the violet to near-IR region in the wide temperature range 13 K-320 K. While the two others show a rather weak emission. Measurements have been carried out in the 350-1150 nm spectral range. The photoluminescence spectra exhibit seven transitions. Some bands have been appeared only at certain temperature range. Below and above this temperature range, these bands have been disappeared. The changes of intensity, band position and broadening versus temperature have been investigated. A multi level model has been proposed to explain the photophysical processes and temperature dependence of PL spectra.