Modification of Optical Band Gap and Surface Morphology of NiTsPc Thin Films

We demonstrate the effects of solvent treatment on the optical band gap and surface morphology of nickel (ii) phthalocyanine tetrasulfonic acid tetrasodium salt (NiTsPc) thin films. The optical band gap and surface morphology modifications are carried out by immersing the films in chloroform for different immersion times until the optimized time (60 min) is found. A Tauc plot is used to calculate the optical energy gaps, which are found to be about 2.70–2.85 eV and 1.43–1.50 eV, in the B and Q bands respectively. AFM topography shows that more granular structures have been formed upon the optimized immersion time. Photoluminescence (PL) quenching occurs in the solvent-treated NiTsPc film incorporated with a tris(8-hydroxyquinolinato)aluminium (Alq3) layer. This PL quenching indicates that the charge carrier transport is more efficient at the interface between NiTsPc/Alq3 as a result of the solvent treatment.