Effect of gold nanoparticles density grown directly on the surface on the performance of organic solar cell

The plasmonic effect of gold nanoparticles has been used in this work to enhance light energy absorption in organic solar cells, to compensate for high light-transmissivity in the active material due to its low thickness. It was found that the density of the nanoparticles grown in the device had a certain critical effect on the performance of the device; where the performance increases with higher nanoparticle density and is optimum when the nanoparticles are grown up for 30 min, which produces a nanoparticle density as high as ca. 125 particles/ μm2. In these conditions, an improvement as high as 83% of the original device can be obtained. The size of the nanoparticles was also found to have a profound effect on the device performance, in which an increase in nanoparticle correlates with a decrease in performance. This is attributed to an increase in the surface roughness at the interface between the active materials and the PEDOT:PSS as the size increases. Gold nanoparticle preparation and a possible mechanism underlying the improvement of the device performance upon the presence of gold nanoparticles will be discussed.