Photosensitizer PCBM tuning of azo dyes-based composites: Third-order nonlinear optical properties

New organic composites with significant third-order nonlinear optical properties have potential applications in photoelectronic and photonics, such as optical limiting and optical switching. Six new azo dye-based composites have been designed and prepared. The linear optical absorption properties were studied by the UV–Vis spectrum and the band-gaps of the samples were determined using the optical method. The third-order nonlinear optical (NLO) properties were investigated by standard Z-scan. The influence of the fullerene derivative (Iliopoulos et al., 2013; Iliopoulos et al., 2013) [6, 6] -phenyl C61 butyric acid methyl ester (PCBM) on the third-order NLO properties was discussed. The third-order NLO susceptibility χ(3) increases firstly with PCBM content, then decrease afterward, and the peak appears at about 0.30 wt%. The results revealed that the third-order nonlinear susceptibility χ(3) and the molecular second hyperpolarizability γ of these composites are of the order of 10−16 (m/V)2 and 10−40 m5V−2, respectively. And the Figures Merit T and W of 1, 2, 3, 4, 5, and 6 meet the all-optical switching requirements of T<1 and W>1. Hence, 1, 2, 3, 4, 5, and 6 are promising candidates for applications in all-optical switching. This work can provide a reference for design new third-order NLO materials.