Effect of WS2 nanoparticles on the current-voltage characteristics of a polymer solar cell

Abstract

The paper presents the results of studies of the effect of tungsten disulfide nanoparticles on the optical and electrotransport characteristics of PEDOT: PSS thin films in polymer solar cells. Tungsten disulfide (WS₂) nanoparticles were obtained by laser ablation in isopropyl alcohol. The average size of nanoparticles were determined by dynamic light scattering and is ~38 nm. The concentration of WS₂ nanoparticles in the solution was calculated based on the density of the WS₂ substance. The absorption spectrum of nanoparticles in isopropyl alcohol has been measured. Two bands are observed in 500-900 nm regions, which are associated with direct exciton transitions A1 and B1 in two-dimensional transition metal dichalcogenides with 2H phase. WS₂ nanoparticles were added in PEDOT: PSS solution and thin films were deposited from the prepared
solution by spin-coating. PEDOT: PSS thin films doped with WS₂ were studied by atomic force microscopy (AFM). The arithmetic mean deviation of the surface roughness (Ra) was estimated. Doping with WS₂ nanoparticles leads to the increase in Ra of PEDOT: PSS thin films. The optical absorption spectra of doped films have been measured. Also, doping PEDOT: PSS with WS₂ nanoparticles results in a long-wavelength shift of the PEDOT absorption maximum. The optimal concentration of WS₂ nanoparticles for the preparation of doped PEDOT: PSS thin films is determined, at which the film resistance decreases by almost 2 times, the recombination resistance of charge carriers increases by 4.7 times, and the efficiency of the polymer solar cell increases to 1.94 %.