New quinacridone derivatives: Structure-function relationship exploration to enhance third-order nonlinear optical responses

Abstract

Exploiting synergistic cooperation between multiple sources of optical nonlinearity, we report the design, synthesis, and the third-order nonlinear optical (NLO) properties of a series of quinacridone-based materials with condensed π-systems, and sterically regulated inter-aryl twist angles. By introducing dicyanoethylene groups not only successfully modified the structures and photoelectric properties of the chromophores but also led to the superior third-order NLO properties. The relationships between molecular structure and mechanisms of the enhanced nonlinear refractive index were illuminated by spectroscopic, electrochemical, and Z-scan measurements. Combined with quantum chemical calculations, the test data and theory calculations were verified. The maximum nonlinear absorptive coefficients (χ(3)) in these materials based on chromophore QA-B2 is 15.456 × 10−13 esu, which is more than 5 times higher than that of mono-modified QA. Our results clearly suggest that quinacridone-based materials have good photo-thermal stability and large third-order NLO properties, are very promising for integrated NLO devices.