Perylenediimides (PDIs) are versatile organic compounds. Broad and strong absorption of visible light, semiconducting properties, easiness of structural modification and high stability make PDIs good candidates for novel optoelectronic and photocatalytic applications. PDIs can find use in fields where photosensitizing properties are desirable, like medicine, photodynamic therapy, photocatalysis, photopolymerization and air purification. Key features of PDIs, like absorption spectrum, HOMO and LUMO energy, emission spectrum, solubility and aggregability, can be modified according to the intended use. In our work, we investigate effects of various substituents with different electronic effects on photophysical properties of PDIs. Such approach allows to alter HOMO and LUMO energy according to needs. Our aim was to optimize structure of PDI derivatives for photosensitizing purposes. Density functional theory calculations and photophysical measurements were used to determine best PDI derivatives. Selected PDI derivatives were synthesized in two steps with good yields from commercially available substrates. Absorption and emission spectra of obtained PDIs were measured. We found PDI derivatives based on a Donor-Acceptor structure had superior photophysical properties. Moreover some of Donor-Acceptor based PDIs most likely exhibit Thermally Activated Delayed Fluorescence (TADF) phenomenon. Donor-Acceptor based PDI derivatives might be a solution for low efficiency of organic photosensitizers.
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