Graphene:silver nanowire composite transparent electrode based flexible organic solar cells with 13.4% efficiency

Abstract

Transparent conductive electrodes are key to flexible organic solar cells (OSCs) to achieve remarkable performance. Herein, flexible OSCs are fabricated using graphene and Ag nanowire (NW) composite transparent conductive films (GR&AgNWs) as an emerging electrode. The electrode exhibits extremely good optical and electrical properties. To enhance the interface contact, a thin film of highly conductive poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonate) (PH1000) was used to modify the rough surface of GR&AgNWs. It also avoids work function mismatch between the electrode and interface layer. Therefore, the resultant GR&AgNWs/PH1000 hybrid electrode based non-fullerene flexible OSCs yield a high power conversion efficiency (PCE) of 13.44% with an open circuit voltage (V_oc) of 0.829 V, a short-circuit current density (J_sc) of 23.20 mA cm⁻² and a fill factor (FF) of 69.82%. Besides, the devices obtain unique mechanical flexibility. It is possible to retain 84.6% of the initial PCE after bending one thousand times at a harsh bending radius (r = 2 mm), which is mainly attributed to the flexibility of the GR&AgNW electrode. This work confirms that GR&AgNW electrodes are a promising candidate to replace ITO and open an avenue to fabricate excellent performance flexible OSCs for future potential applications due to low cost and more environmental stability and friendliness of the electrode.