Highly flexible, high-performance perovskite solar cells with adhesion promoted AuCl3-doped graphene electrodes

Super flexible TCO-free FAPbI(3-x)Br(x) planar type inverted perovskite solar cells with a 17.9% power conversion efficiency under 1 sun conditions were demonstrated by introducing an APTES (3-amino-propyl triethoxysilane) adhesion promoter between a PET flexible substrate and a AuCl3-doped single-layer graphene transparent electrode (TCE). Due to the formation of covalent bonds by the APTES inter-layer, the AuCl3-GR/APTES/PET substrate had excellent flexibility, whereas the AuCl3-GR/PET substrate and the ITO/PET substrate had significant degradation of the sheet resistance after a bending test due to the break-off or delamination of AuCl3-GR from the PET substrate and the cracking of ITO. Accordingly, the perovskite solar cells constructed on the AuCl3-GR/APTES/PET TCE substrate exhibited excellent bending stability and they maintained their PCE at over 90% of the initial value after 100 bending cycles at R >= 4 mm.