DNanoscale consecutive self-assembly of thin-film molecular materials for electrooptic switching. Chemical streamlining and ultrahigh response chromophores

A broadly applicable approach to formation of self-assembled organic electrooptic superlattices for highspeed switching is reported. This two-step one-pot method involves (i) layer-by-layer covalent self-assembly of intrinsically acentric monolayers of a new high-hyperpolarizability donor-acceptor aminophenylbenzothiazolpyridinium chromophore (beta(0.65 eV)(calcd) = 1620 x 10(-30) cm(5) esu(-1)) on hydrophilic substrates and (ii) in-situ chromophore deprotection concurrent with self-limiting capping/planarization of each chromophore layer with octachlorotrisiloxane. The resulting organic films are characterized using a combination of physicochemical methodolgies including synchrotron X-ray specular reflectivity, angle-dependent polarized second harmonic generation spectroscopy, optical spectrometry, X-ray photoelectron spectroscopy, and advancing contact angle measurements. The superlattices exhibit very large second-order responses, chi((2)) approximate to 370 pm/V, and a large macroscopic electrooptic coefficient, r(33) approximate to 120 pm/V, is estimated at lambda(0) = 1064 nm.