Electro‐Optic Activity in Excess of 1000 pm V⁻¹ Achieved via Theory‐Guided Organic Chromophore Design

Abstract High performance organic electro‐optic (OEO) materials enable ultrahigh bandwidth, small footprint, and extremely low drive voltage in silicon‐organic hybrid and plasmonic‐organic hybrid photonic devices. However, practical OEO materials under device‐relevant conditions are generally limited to performance of ≈300 pm V⁻¹ (10× the EO response of lithium niobate). By means of theory‐guided design, a new series of OEO chromophores is demonstrated, based on strong bis(4‐dialkylaminophenyl)phenylamino electron donating groups, capable of EO coefficients (r₃₃) in excess of 1000 pm V⁻¹. Density functional theory modeling and hyper‐Rayleigh scattering measurements are performed and confirm the large improvement in hyperpolarizability due to the stronger donor. The EO performance of the exemplar chromophore in the series, BAY1, is evaluated neat and at various concentrations in polymer host and shows a nearly linear increase in r₃₃ and poling efficiency (r₃₃/E_p, E_p is poling field) with increasing chromophore concentration. 25 wt% BAY1/polymer composite shows a higher poling efficiency (3.9 ± 0.1 nm² V⁻²) than state‐of‐the‐art neat chromophores. Using a high‐ε charge blocking layer with BAY1, a record‐high r₃₃ (1100 ± 100 pm V⁻¹) and poling efficiency (17.8 ± 0.8 nm² V⁻²) at 1310 nm are achieved. This is the first reported OEO material with electro‐optic response larger than thin‐film barium titanate.