Insights into Growth of a Photoactive Layer Based on Perylene Diimide Bearing Alkoxysilane Groups

The chemical grafting of organic photosensitizers onto solid surfaces has gained increasing attention lately as an effective strategy for the formation of stable, functional layers, with promising applications in areas such as antimicrobial coatings and optoelectronic devices. In this work, a perylene diimide (PDI) derivative bearing alkoxysilane groups, APTES-PDI-APTES, was synthesized and chemically grafted onto a glass surface. The presence of two alkoxysilanes enabled competing processes to occur, i.e., condensation reactions, which led to the formation of complex multilayer structures, and covalent bonding to the glass surface. The influence of deposition process parameters, such as solvent polarity and immersion time, on the chemical structure and the morphology of the resulting layer was studied using X-ray photoelectron spectroscopy, Raman spectroscopy, and atomic force microscopy. The singlet oxygen photogeneration was tested using an indirect detection method, proving that after immobilization, APTES-PDI-APTES retains its photosensitizing properties. These findings highlight the influence of the process parameters on the development of the PDI-containing multilayer and its potential application as a heterogeneous source of singlet oxygen.