Absorption enhancement and efficiency improvement of an organic solar cell embedded with core–shell Au@ITO nanoparticles

In this paper, we propose a new design of plasmonic organic solar cells (OSCs). It consists of a protective layer of SiO2, an anti-reflective glass of ITO, a compact buffer of PEDOT:PSS, an absorbing organic material of P3HT:PCBM, and a reflective layer of Al. A square periodic array of core–shell nanoparticles (Au@ITO NPs) is embedded in the active layer of P3HT:PCBM in order to enhance the absorption of OSC. Although ITO coating slightly reduces efficiency, it prevents the oxidation of gold NPs and increases the OSC lifetime. We study the effect of numerous parameters such as the core radius, shell thickness, and core material on the optical absorption by solving Maxwell’s equations using the three-dimensional finite-difference time-domain method. The drift–diffusion and Poisson’s equations are solved with an in-house software tool by discretizing the solar cell using the finite element method. To the best of our knowledge, this paper is the first to apply the real model of trap-assisted recombination and Auger recombination of used materials to the simulations to match them with the experimental results. The numerical results show the proposed OSC embedded with Au@ITO NPs has the built-in potential of 2.9 V, short-circuit current of 16.63 mA/cm2, the open-circuit voltage of 1.14 V, maximum power of 17.25 mW/cm2, fill-factor of 0.91, the conduction band of 2.8 eV, electron quasi-Fermi level of 2.35 eV, hole quasi-Fermi level of 0.6 eV and an efficiency of 17.25%. Furthermore, the performance of the proposed OSC has an improvement of 25% compared to conventional OSCs.