Third-order nonlinear optical properties of P3DDT-CdS nanocomposites

► Poly(3-dodecylthiophene)-CdS as third-order nonlinear optical material. ► Nonlinear optical properties of P3DDT-CdS is enhanced by CdS and P3DDT. ► Coherent oscillation of the conduction band electrons in the nanocomposites. ► The valence band offset of P3DDT-CdS is higher than conduction band offset. ► Electron-hole recombination in the P3DDT for the P3DDT-CdS.