Optical properties of P3HT:tributylphosphine oxide-capped CdSe nanocomposites

The optical properties of nanocomposite layers prepared by incorporation of tributylphosphine oxide (TBPO)-capped CdSe nanocrystals (NCs) in a P3HT polymer matrix are studied using different nanocrystal concentrations. Reflection spectra analyzed through Kim oscillator model lead to the determination of optical constants such as refractive index n, extinction coefficient k, dielectric permittivity e and absorption coefficient α.Using the common Cauchy, Drude–Lorentz, Tauc and single-effective-oscillator theoretical models, we have determined the values of static refractive index ns and permittivity es, plasma frequency \(\omega_{\text{p}}\), carrier density N, optical band gap Eg and oscillator and dispersion energies E0 and Ed, respectively. It is found that TBPO-capped CdSe NCs concentration affects the optoelectronic parameters of the nanocomposite thin films. Moreover, the disorder of this hybrid system is also studied by the determination of Urbach energy, which increases with TBPO-capped CdSe concentration.