Unveiling the enhanced optical limiting of polyaniline – Fullerene composite investigated by z-scan.

The reverse saturable absorption (RSA) and optical limiting (OL) mechanisms of polyaniline (PANI) and fullerene doped PANI (PANI-C60) solutions were investigated by open-aperture z-scan studies, using a nanosecond pulsed Nd:YAG laser operating at 532 nm wavelength as the excitation source. The nonlinear absorption coefficient (β), OL threshold, and imaginary part of nonlinear susceptibility ( χ i (3) ) of PANI and PANI-C60 solutions were determined for three different laser input pulse energies and are found to be in the order of 10−9 cm/W, 106 W/cm2, and 10−10 esu respectively. The results showed enhanced OL efficiency for the PANI-C60 solution, making it a promising candidate for applications in optoelectronics and optical limiting. The transmission electron microscope (TEM) images revealed the uniform distribution of C60 of particle size in the range of 5–10 nm in the PANI matrix. The composite formation of PANI-C60 was confirmed by Fourier transform infrared spectroscopy (FTIR). The presence of C60 and its charge transfer complex (CTC) formation with PANI are responsible for the enhanced OL efficiency. The linear refractive index values were measured using UV–Visible absorption spectra and compared with the theoretical values. The investigation of the OL mechanism and the calculation of its associated NLO parameters for PANI and PANI-C60 solutions are reported for the first time. [Display omitted] • The NLO absorption mechanism of PANI and PANI-C60 composite was examined in this study. • The β , OL threshold, and χ i (3) of PANI and PANI-C60 composite were determined for three laser input pulse energies. • The findings revealed that PANI-C60 composite had better nonlinear absorption and OL properties than PANI. • Investigation of OL mechanism and calculation of NLO parameters for PANI and PANI-C60 solutions in the first time. • The results imply, PANI-C60 composites are considered to be promising materials in OL and optoelectronic devices. [ABSTRACT FROM AUTHOR]