Optical Engineering of Uniformly Decorated Graphene Oxide Nanoflakes via in Situ Growth of Silver Nanoparticles with Enhanced Plasmonic Resonance

A nanocomposite of silver-nanoparticle-decorated graphene oxide (GO-Ag NPs), enhanced by the surface plasmon resonance (SPR) effect, improved the performance of polymer solar cells (PSCs). The GO-Ag NPs were fabricated in situ via ultraviolet (UV) irradiation (254 nm) of GO and an aqueous solution of AgNO3. The photoexcited GO accelerated reduction of Ag+ ions into silver nanoparticles (Ag NPs) upon UV irradiation, and the Ag NPs spontaneously deposited on the GO nanoflakes because the numerous functional groups on GO enable efficient adsorption of Ag+ ions and Ag NPs via electrostatic interactions. The strong coupling between the SPR effect of GO-Ag NPs and incident light offers the probability of improved light absorption and corresponding exciton generation rate with enhanced charge collection, resulting in significant enhancement in short-circuit current density and power conversion efficiency (PCE). Therefore, the PCE of PSCs based on poly[4,8-bis(2-ethylhexylthiophene-5-yl)-benzo[1,2-b:4,5-b]dithiophene-2,6-diyl]-alt-[2-(2-ethylhexanoyl)thieno[3,4-b]thiophen-4,6-diyl] and [6,6]-phenyl C71-butyric acid methyl ester has been substantially elevated to 7.54% from 6.58% by introducing GO-Ag NPs at the indium tin oxide/poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid interface. In addition, the excellent properties of GO-Ag NPs, including its simple preparation, processability in aqueous solution, cost-effectiveness, and sustainability, make it suitable for the roll-to-roll manufacturing of PSCs.