Enhanced Absorption in Organic Solar Cells Using Core-Shell Iron-ZnO Nanoparticles: Optical and Numerical Simulations

Abstract

This paper presents a detailed numerical and optical simulation analysis of iron (Fe) nanoparticles (NPs) with zinc oxide (ZnO) shells embedded in a square periodic array within the active layer of organic solar cells (OSCs). Utilizing the Finite Difference Time Domain (FDTD) method, we first calculate the intrinsic absorption of P3HT:PCBM. Following this, Fe-ZnO NPs are introduced into the active layer, and their absorption properties are analyzed and compared to the intrinsic absorption. The Absorption Enhancement (AE) metric is employed to optimize the period, thickness, and edge length of the rectangular prism Fe NPs to achieve maximum AE. Additionally, AE is compared in similar structures with different core materials, including gold (Au), silver (Ag), and aluminum (Al). The proposed structure, characterized by a thick shell on the top and base faces, demonstrates that Fe NPs can achieve an AE 1.282 times greater than the intrinsic absorption, and 1.13, 1.165, and 1.07 times more than Au, Ag, and Al, respectively. Notably, Al exhibits greater absorption enhancement than Au and Ag, indicating its potential as a future candidate. Furthermore, the electric field and absorption density are investigated, revealing how near-field plasmonics can significantly enhance absorption within the active layer, even in the red part of the spectrum. Iron NPs offer several advantages over traditional noble metal NPs, including cost-effectiveness, guaranteed biodegradability in OSCs, highest AE, and interesting magnetic properties that can influence excitons and electron-hole separation and velocity. These factors make Fe NPs an attractive option for enhancing the efficiency of OSCs.