Synthesis and characterization of gold and silver nanoparticles for enhanced light collection in organic solar cells

Abstract

The study aims to synthesize plasmonic nanoparticles (NPs) using the chemical reduction method and incorporate them into poly(3,4-ethylene dioxythiophene): poly(styrene sulfonate) (PEDOT: PSS) for light scattering. The plasmonic NPs were chosen because of their remarkable physical, chemical, and optical properties. Chloroauric acid, silver nitrate and copper sulphate were reduced by sodium borohydride to obtain gold (Au), silver (Ag) and copper (Cu) NPs, respectively. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and ultraviolet-visible spectroscopy were used to characterize the samples. The TEM results showed spherical shapes of Au and Ag NPs with average grain sizes of 23.7 ± 0.5 and 5.0 ± 1.2 nm, respectively. The grain sizes of Cu NPs containing 5, 10, and 15 mM CuSO4 were 6.01 ± 0.89 nm, 17.32 ± 0.55 nm, and 32.00 ± 0.75 nm, respectively. The NPs were deposited in PEDOT: PSS and spin-coated on a glass substrate followed by the blend of poly(3-hexylthiophene): phenyl-C61-butyric acid methyl (P3HT: PCBM) ester. The UV-Vis spectroscopy revealed that NPs are absorbing in the visible range by showing plasmonic resonance at approximately 534 nm for Au, 408 nm for Ag and 560 for Cu NPs along with peaks of PEDOT: PSS, PCBM and P3HT at 353, 333 and 445 nm respectively. The X-ray diffraction (XRD) patterns confirmed the FCC structure of both NPs with (111), (200), (220), and (310) phases in which the (111) peak was the most intense. From Raman spectroscopy measurements, the main peaks associated with P3HT: PCBM, PEDOT: PSS were observed. Organic solar cells (OSC) with and without nanostructures were fabricated with P3HT: PCBM as the active layer, and PEDOT: PSS as a hole transport layer. The current-density (J-V) characterizations were performed. From the J-V measurements, the OSCs containing 20 μL of Cu NPs had the highest efficiency of 8.77 %. From this study, NPs showed the potential to improve light absorption in OSCs.