Efficient planar heterojunction perovskite solar cells fabricated via roller-coating

We introduce efficient planar heterojunction CH₃NH₃PbI₃ perovskite solar cells (PSCs) fabricated with a roller coating process under ambient conditions. The perovskite films were prepared with a roller coating of lead iodide (PbI₂) and a spin coating of methylammonium iodide (MAI), a successive roller coating of PbI₂ and MAI, and a spin coating of PbI₂ and MAI as a reference film. The PSCs with roller-coated perovskite films were systemically compared to a reference PSC with spin-coated PbI₂ and MAI. In order to investigate the effect of roller coating on PSC performance, scanning electron microscopy (SEM), UV-vis absorption, and X-ray diffraction (XRD) measurements were performed. With the PbI₂ roller coating, the PSCs showed excellent power conversion efficiencies (PCEs) of up to 9.52% under a standard 1-sun condition, quite comparable to the spin-coated PSCs. In addition, the PSCs with the all roller-coated PbI₂ and MAI showed high PCEs of up to 6.421%, and with the aid of an additive the PCEs were further enhanced of up to 7.356%. These results support the conclusion that roller coating can be used for the facile and cost-effective manufacture of high-efficiency solution-based PSCs.