Photoluminescence temperature quenching of H₂TPP and ZnTPP tetraphenylporphyrins thin films

Abstract

Photoluminescence temperature quenching of tetraphenylporphyrins thin films on silicon substrates have been investigated. Free-based tetraphenylporphyrin (H2TPP) and Zinc-tetraphenylporphyrin (ZnTPP) films were obtained by thermal evaporation in vacuum. The photoluminescence properties of these samples are observed in the wide temperature range from 77 to 300 K. The temperature-depended photoluminescence intensity of ZnTPP exhibits abnormal behaviour. An increase in the photoluminescence intensity is observed in the temperature range of 77-180 K. We suppose that charge carriers are trapped by non-radiative centres when the temperature decreases down to 77 K. The release of carriers occurs with a further temperature increase. In addition, there are sharp increases in the luminescence intensity of thin H2TPP and ZnTPP films at a temperature of 270 K, which are associated with a second-order phase transition.