Properties of Flexible Bulk Heterojunction Organic Solar Cells with Gold Nanoparticles Embedded in Poly(3,4-ethylenedioxythiophene): Poly(styrenesulfonate) Buffer Layer

We investigated the effects of the size (10, 40 and 80 nm) of gold nanoparticles (Au NPs) on the performance of flexible organic solar cells (OSCs) incorporated within a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) buffer layer. Au NPs improved the power conversion efficiency (PCE) of OSC devices. The PCE value increased from 2.5 to 2.8% as the particle size of Au NPs increased from 10 to 80 nm. It seems that Au NPs provide near-field enhancement through excitation of the surface plasmon resonance (SPR) effect, resulting in the enhancement of the light absorption into the buffer layer. OSCs with the structure of polyethylene naphthalate (PEN)/indium tin oxide (ITO)/PEDOT:PSS-Au NPs/poly(3-hexylthiophene-2,5-diyl):(6,6)-phenyl-C-61 butyric acid methylester (P3HT:PCBM)/lithium fluoride (LiF)/aluminum (Al) exhibited an improvement in PCE mainly due to the enlarged surface roughness of the PEDOT:PSS, which may increase charge collection.