Optical and electrical evaluation of a nylon 11-ZnO film incorporation in disodium phthalocyanine heterostructures

Abstract

Disodium phthalocyanine (Na₂Pc) has been considered as promising organic semiconductor for optoelectronic applications, however, Na₂Pc-based devices are not being fully studied. To study the Na₂Pc as active layer for optoelectronic devices, and also the effect of the incorporation of a nylon 11-ZnO film within the device heterostructure, in this work two heterojunction cells of Ag/Na₂Pc + TCNQ/triphenylamine/p-Si/Al and Ag/nylon 11-ZnO/Na₂Pc + TCNQ/triphenylamine/p-Si/Al were fabricated by vacuum thermal evaporation technique. The topography of the heterostructures was analyzed by atomic force microscopy. Later, the films that form the heterostructure were optically characterized by Ultraviolet-visible spectroscopy and the optical band gap and the Urbach energy were obtained. The values of the optical gap for the films are between 2.08 and 2.93 eV. The value of Urbach energy is lower for the pristine triphenylamine film, and higher for the film composed of nylon and ZnO. Moreover, the two heterostructures present a strong photoluminescence in the visible region. On other hand, by introducing the nylon 11-ZnO film in the heterostructure shows an important increase of the short circuit current density (Jsc), conductivity and photocurrent values, indicative of a better mobility and more carriers generation. For this heterostructure a mean 79.7% external quantum efficiency and 0.48 mA/cm² Jsc were obtained. These results indicate that these heterostructures can be used toward organic solar cell applications and remark on the large effect of the nylon 11-ZnO dielectric film addition on their performance.