Enhanced performance of polymer solar cells with a monolayer of assembled gold nanoparticle films fabricated by Langmuir–Blodgett technique

We reported the enhanced performance of polymer solar cells with the blend of poly (2-methoxy-5(2′-ethylhexyloxy)-1,4-phenylene-vinylene) (MEH-PPV) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) as active layer by incorporation of an assembled gold nanoparticle (Au NP) monolayer. The dense Au NP monolayer has been fabricated by Langmuir–Blodgett (LB) assembly and positioned between the transparent electrode ITO and the anode-modification PEDOT:PSS [poly (3,4-ethylenedioxythiophene):poly(styrene sulfonate)] layer, resulting in the device architecture of ITO/Au/PEDOT:PSS/MEH-PPV:PCBM/Al. We attribute the performance improvement to the localized surface plasmon resonance (LSPR) effect of Au NP films, which could lead to the increased absorption of the active layer. The parameters (nanoparticle size and interparticle distance) that govern this SPR effect have been optimized by selecting various sizes of Au NPs and controlling the LB assembly conditions. We observed ∼10–20% enhancement in power conversion efficiency for all the devices with the Au NP monolayer.