Utilization of 7,7-bis(N, N-diethylethylenediamino)-8,8-dicyanoquinodimethane molecular crystal as an organic optical waveguide

Tetracyanoquinodimethane (TCNQ) derivatives are known to exhibit diverse properties enabling their employment in molecular materials and biological applications. TCNQ derivatives with primary/secondary amines commonly known as diaminodicyanoquinodimethanes (DADQs); a donor-π-acceptor system are generally stable with zwitterionic character. Till date, solid and solutions of DADQs have been investigated exclusively with respect to fluorescence (FL) property and the non-linear optical property (especially second harmonic generation (SHG)), among solid DADQs. Nevertheless, as yet, the optical waveguiding aspect has not been explored on any DADQs. Therefore, herein, we report the application of 7,7-bis ( N,N -diethylethylenediamino)-8,8-dicyanoquinodimethane (BDEDDQ) crystals as an efficient active organic optical waveguide material. A two-dimensional (2D) micro-crystal length of ≈119 μm and a one-dimensional (1D) micro-crystal length of ≈255 μm has been taken into consideration, and a continuous wave laser of visible light (405 nm) was utilized for the waveguiding study. Fluorescence transduction of the produced blue light confirmed the effective active waveguiding property of the micro-crystals. Moreover, the field emission scanning electron micrographs of 1D and 2D micro-crystal optical waveguides displayed a smooth surface, and defect-free morphology; this provides additional evidence of the optical waveguide's efficient light coupling. The effective light confinement in the micro-crystals offers a way for a variety of photonic applications.