Highly efficient organic solar cells enabled by interface modification of silver nanowires flexible transparent electrode

Flexible transparent electrodes (FTEs) are crucial for achieving high performance in flexible organic solar cells (OSCs). Silver nanowires (Ag NWs) FTEs with low resistance, high optical transmission, and excellent mechanical flexibility have attracted extensive attention. Herein, Ag NWs/PH1000(with acid treatment (AT))/PEI FTEs were obtained by low-temperature acid-treated and modified by polyethyleneimine (PEI). Compared with Ag NWs FTEs, the surface roughness of Ag NWs/PH1000(with AT)/PEI FTEs reduced from 3.65 nm to 1.61 nm, which performs a superior conductivity and better wettability. The lower roughness facilitates ohmic contact between the active layers and FTEs, thus improving charge transport and collection. Finally, an optimal power conversion efficiency (PCE) of 16.19% for flexible OSCs was achieved by employing Ag NWs/PH1000(with AT)/PEI as FTEs and PM6:BTP-eC9 as the active layer. Remarkably, the flexible devices show excellent mechanical flexibilities which can retain 90% of the initial efficiency after 1000 bending cycles. The results demonstrate the effectiveness of using Ag NWs/PH1000(with AT)/PEI FTEs in improving the efficiency of flexible OSCs.