Functionalization tuning of the nonlinear optical response of perylene diimide derivativatives

Abstract

The synthesis and characterization of perylene diimide (PDI) derivatives functionalized by electron donating groups at their bay and imide positions have been reported. Five different PDI derivatives were synthesized and their linear optical and third-order non-linear optical (NLO) properties were studied. The NLO measurements of the synthesized PDI derivatives were conducted under nanosecond (ns) and femtosecond (fs) laser excitation conditions, using the Z-scan technique employing 4 ns, 1064/532 nm and 70 fs, 800/400 nm laser pulses. A noticeable tuning of the NLO character between the synthesized PDI derivatives was observed, revealing the importance of the functionalization of the PDI core by the anchored electron donating units. The largest NLO value was achieved by the incorporation of p-aminoazobenzene at the PDI bay position. The experimental NLO findings and trends were further corroborated with theoretical computations of UV-Vis spectra and NLO response, performed using density functional theory (DFT). It was found that both experiments and simulations satisfactorily convey changes in the NLO response between the studied PDI derivatives. The mechanism that could lead to an efficient tuning of the PDIs’ NLO response, is associated with the modification of their electronic character resulting by the proper PDI core functionalization.