Unraveling the electrical energy loss in silver nanowire electrodes for flexible and Large-Area organic solar cells

Although the transparency and sheet resistance of silver nanowire (AgNW) electrodes are comparable to those of rigid indium-tin-oxide electrodes, flexible organic solar cells (FOSCs) are still less efficient than their rigid counterparts. Herein, by recording the microscopic photocurrent images of AgNW-based FOSCs in operation, it has been revealed that the limited lateral charge collection range of AgNW leads to inevitable electrical energy loss. The regulation of carrier mobility and energy level of adjacent ZnO electron transport layer increases the effective collection range of AgNWs by 1.8 times and uniform the electrical potential distribution in FOSCs. The D18:Y6:PC71BM-based FOSCs achieve a power conversion efficiency of approaching 18%. Moreover, the performance drop of large-area FOSCs is significantly reduced due to the improved charge collection on large area scale. This work provides an intuitive insight into the electrical energy loss mechanism of AgNW electrodes and demonstrates an electric field regulation strategy in FOSCs.