[15a-A402-1~10] 12.5 Organic solar cells

[15a-A402-5] Photocurrent Collection Length and the Fill Factor of Mixed-Composition Metal Halide Perovskite Solar Cells

〇Richard Murdey¹, Yasuhisa Ishikura¹, Yuko Matsushige¹, Kento Otsuka¹, Ruito Hashimoto¹, Minh Anh Truong¹, Tomoya Nakamura¹, Atsushi Wakamiya¹ (1.Kyoto Univ.)

Keywords:charge carrier recombination, fill factor, optical gap

The low fill factor we observe in mixed-composition perovskite based devices is accounted for by introducing a voltage-dependent photocurrent collection efficiency. A key parameter of this model, the collection length, depends on both the mobility and the lifetime of the charge carriers. Thus, the extracted collection lengths allow quick and direct evaluation of the electrical quality of the perovskite films. To demonstrate this, devices are prepared with different halide composition ratios. The fill factors under simulated solar radiation decrease as the ratio of bromine ions to iodine ions in the perovskite increases. The collection lengths also decrease, pointing to lower charge carrier mobility and/or shorter charge carrier lifetime in the perovskite layer. Such changes to the charge collection properties must be taken into account when adjusting the optical gap via compositional engineering.