Design and Realization of New Generations of Organic Chromophores for Electro-Optics
Hu Kang, Antonio Facchetti, Hua Jiang, Elena Cariati, Stefania Righetto, Renato Ugo, Luca Beverina, Marika Morone, Giorgio Pagani and Tobin J. Marks
There is great current interest in developing molecule-based electro-optic (EO) materials for opto-electronic and photonic technologies such as high-speed optical communications, integrated optics, and optical data processing and storage. Here we present the design rationale, synthesis,and molecular properties of two new organic chromophore classes enabling very large EO response along with new methodologies for self-assembling them in a non-centrosymmetric fashion. In the first class, we demonstrate that disruption of the p-conjugation via a sterically-induced molecular twisting results in unusual molecular characteristics and unprecedented hyperpolarizabilities (µb values as high as —488,000 x 10 -48 esu at 1907 nm). Guest-host poled polymers containing p-twisted chromophores exhibit very large electro-optic coefficients (r 33) up to 320 pm/V at 1310 nm. Molecules of the second class enable the fabrication of acentric, high-quality, transparent, micrometer-thick films via physical vapor deposition. These systems are thermally stable and electro-optical-active films (r33 up to ~20 pm/V) are prepared in few hours as a consequence of the pyridine-hydroxycarbonyl head-to-tail hydrogen bonding.