Brush-painted flexible organic solar cells using highly transparent and flexible Ag nanowire network electrodes

We report on the highly flexible and cost-efficient brush painting of flexible organic solar cells (FOSCs). Brush painting was applied for all of the solution-based layers of FOSCs-an Ag nanowire (NW) anode, a poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) hole transporting layer, a poly(3-hexylthiophene) (P3HT)- and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM)-based active layer, and a ZnO electron transporting layer. By the simple and fast brush painting of the Ag NW network with a low sheet resistance of 26.4 Ω/square, a high transmittance of 81.8%, and superior flexibility, we can avoid the use of typical sputtered Sn-doped In2O3, which is used as anode electrodes in typical FOSCs. The P3HT:PCBM-based FOSCs fabricated by brush-painting processes showed a short circuit current of 7.276 mA/cm2, an open circuit voltage of 0.574 V, a fill factor of 49.20%, and a power conversion efficiency of 2.055%. The successful operation of brush-painted FOSCs indicated that brush painting is a promising ultra-low-cost and fast coating process for the fabrication of solution-based cost-efficient FOSCs.