Novel Multifunctional Umbrella Molecule Material Combining Photoelectric Conversion and Second-Order Optical Nonlinearities in Langmuir−Blodgett Monolayers

Abstract

A dipolar two-dimensional multifunctional (D-π)3-A dye molecule, 2,4,6-tris(4-(N-methyl-N-hexadecylamino)styryl)pyrylium tetrafluoroborate (P3) was synthesized. The dye molecule was successfully transferred onto an ITO electrode or quartz by the Langmuir−Blodgett (LB) technique. The second-harmonic generation (SHG) and photoelectric conversion (PEC) properties of the “molecular umbrella” monolayers were studied under 10 and 40 mN m-1 surface pressure. The different tilt angle of the “molecular umbrella” results in the difference of SHG and PEC properties. For comparison, dipolar one-dimensional molecule 2,6-dimethyl-4-(4-(N-methyl-N-hexadecylamino)styryl)pyrylium tetrafluoroborate (P1) was also investigated. The experimental results show that the SHG and PEC properties of the dipolar two-dimensional molecule (P3) are better than those of the dipolar one-dimensional molecule (P1). For example, under favorable conditions (−100 mV, dissolved O2, 2 mM MV2+, and 4 mM Eu3+), the quantum yields for P3 and P1 monolayers (deposited under 40 mN m-1) are 1.21 and 0.42%, respectively.