High-Performance Flexible Perovskite Solar Cells Enabled by Low-Temperature ALD-Assisted Surface Passivation

Flexible perovskite solar cells (PeSCs) hold great potential as a leading technology for large-scale roll-to-roll production of highly efficient renewable energy sources. To achieve long-term bendability and competitive photovoltaic properties for flexible PeSCs, an efficient strategy is reported for a fully indium-free flexible composite electrode, consisting of solution-processed silver nanowires (AgNWs) conductive network, a sol-gel-derived ZnO protective layer for smoothing the surface, and an atomic-layer-deposited TiO2 passivation layer for eliminating the perovskite decomposition. The synergetic interplay of this electrode stack results in good electrical conductivity, optical transparency, mechanical robustness, and low-temperature processability. With collective optimization of this composite electrode, flexible PeSCs on plastics realize a power conversion efficiency of 17.11%, which is comparable to that of conventional indium-tin-oxide-based device (18.26%). Moreover, flexible PeSCs using this composite electrode are repeatedly bendable, retaining 77% of their initial efficiency after 2000 bending cycles at a radius of 6 mm. Because of the ease of use and remarkable improvement in efficiency, this flexible composite electrode will help to enable the low-cost roll-to-roll processing of flexible PeSCs.