All‐Carbon‐Electrode‐Based Endurable Flexible Perovskite Solar Cells

Endured, low-cost, and high-performance flexible perovskite solar cells (PSCs) featuring lightweight and mechanical flexibility have attracted tremendous attention for portable power source applications. However, flexible PSCs typically use expensive and fragile indium–tin oxide as transparent anode and high-vacuum processed noble metal as cathode, resulting in dramatic performance degradation after continuous bending or thermal stress. Here, all-carbon-electrode-based flexible PSCs are fabricated employing graphene as transparent anode and carbon nanotubes as cathode. All-carbon-electrodebased flexible devices with and without spiro-OMeTAD (2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene) hole conductor achieve power conversion efficiencies (PCEs) of 11.9% and 8.4%, respectively. The flexible carbon-electrode-based solar cells demonstrate superior robustness against mechanical deformation in comparison with their counterparts fabricated on flexible indium–tin oxide substrates. Moreover, all carbon-electrodebased flexible PSCs also show significantly enhanced stability compared to the flexible devices with gold and silver cathodes under continuous light soaking or 60 °C thermal stress in air, retaining over 90% of their original PCEs after 1000 h. The promising durability and stability highlight that flexible PSCs are fully compatible with carbon materials and pave the way toward the realization of rollable and low-cost flexible perovskite photovoltaic devices.