All-Solution-Processed Silver Nanowire Window Electrode-Based Flexible Perovskite Solar Cells Enabled with Amorphous Metal Oxide Protection

Eunsong Lee, Jihoon Ahn, Hyeok-Chan Kwon, Sunihl Ma, Kyungmi Kim, Seongcheol Yun, Jooho Moon

Index: 10.1002/aenm.201702182

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Abstract

Silver nanowire (AgNW)-based transparent electrodes prepared via an all-solution-process are proposed as bottom electrodes in flexible perovskite solar cells (PVSCs). To enhance the chemical stability of AgNWs, a pinhole-free amorphous aluminum doped zinc oxide (a-AZO) protection layer is deposited on the AgNW network. Compared to its crystalline counterpart (c-AZO), a-AZO substantially improves the chemical stability of the AgNW network. For the first time, it is observed that inadequately protected AgNWs can evanesce via diffusion, whereas a-AZO secures the integrity of AgNWs. When an optimally thick a-AZO layer is used, the a-AZO/AgNW/AZO composite electrode exhibits a transmittance of 88.6% at 550 nm and a sheet resistance of 11.86 Ω sq−1, which is comparable to that of commercial fluorine doped tin oxide. The PVSCs fabricated with a configuration of Au/spiro-OMeTAD/CH3NH3PbI3/ZnO/AZO/AgNW/AZO on rigid and flexible substrates can achieve power conversion efficiencies (PCEs) of 13.93% and 11.23%, respectively. The PVSC with the a-AZO/AgNW/AZO composite electrode retains 94% of its initial PCE after 400 bending iterations with a bending radius of 12.5 mm. The results clearly demonstrate the potential of AgNWs as bottom electrodes in flexible PVSCs, which can facilitate the commercialization and large-scale deployment of PVSCs. A pinhole-free amorphous Al-doped zinc oxide (AZO) protection layer dramatically enhances the chemical stability of silver nanowires (AgNWs). Using all-solution-processed amorphous AZO/AgNW/AZO transparent electrodes in flexible perovskite solar cells, it is possible to achieve a power conversion efficiency of 11.23%.