Enhancing power conversion efficiency and anti-bending ability of flexible perovskite solar cells with PEDOT:PSS:Li hole transport layer

Power conversion efficiency (PCE) and anti-bending ability of flexible perovskite solar cells (FPSCs) are largely improved, when poly(3,4-ethylenedioxythiophene) polystyrene sulfonate lithium (PEDOT:PSS:Li) fabricated by the two-step annealing method is used as the hole transport layer (HTL). The PCE of the optimized FPSC achieved 16.83%, which is relatively 6.9% larger than that of the control FPSC. The failure bending cycle, Nf, was defined to characterize the service life of the FPSCs. The optimized Nf achieved 3797, which is 2.6 times the Nf of the control FPSC. During the bending process, the PEDOT:PSS:Li layer retarded the cracking of the ITO layer, and extended the service life of the FPSC. The optical and electrical properties, anti-bending ability and storage stability of PEDOT:PSS:Li were investigated. The layer electrical conductivity, σ, achieved 1320.70 S cm−1. When the bending radius was fixed as 1.0 cm, after 10000 bending cycles, σ remained 1057.90 S cm−1, or 80.1% of the original value, which exhibits satisfactory anti-bending ability. PEDOT:PSS:Li is very potential to function as the HTL in FPSCs.