Study by first-principles calculations of structural and electronic properties of aluminum phthalocyanine hydroxide thin films

Full text: This work tends to investigate the Aluminum Phthalocyanine Hydroxide thin films formation, performing first-principles calculations based on the Density Functional Theory and Time-Dependent Density Functional Theory. The major motivation of this study came in order to explain the experimental results which show distinct AlOHPc molecules aggregations in the formation of thin films by spin-coating technique. The results obtained show a blue shift in the absorption spectrum. Moreover, X-Ray results show it may occur two interplanar distances, which can be used to elucidate the structural properties of the thin films. Molecule film properties, such as X-Ray diffraction, absorption and fluorescence spectrum were characterized. Moreover, several studies investigating all different Phthalocyanine applicabilities increase the interest in the study of suchlike molecules. Firstly, we performed a geometry optimization within the PBE exchange correlation functional. Following this, we carried out TDDFT calculations based on B3LYP functional in order to calculate the UV-vis spectra and the difference density plots. Besides that, it was performed various thin film calculations for different aggregation types to understand the X-Ray diffraction results. Furthermore, to describe the aggregation molecules effect, we calculated the monomer and dimer absorption spectrum. The main results found for monomer show that for the first excited state the largest contribution in the transition is from HOMO to LUMO and exhibits a large oscillator strength resulting in a high intensity. As well, in the different dimer aggregation types, it was noted a blue shift in the UV-VIS spectra, as expected by the experimental results. This results will help up to better understand the photo physics phenomena in the experiments described. (author)