Optimization of PMMA:PCBM Interlayer for MAPbI3/IGZO Phototransistor

[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is well-known as an electron transport layer for perovskite solar cells. Here, the influence of mixed PCBM with polymethyl methacrylate (PMMA) as an interlayer on the device performance of perovskite/IGZO phototransistors is investigated. The PMMA:PCBM composite can not only assist to transfer the photo-generated electrons in perovskite thin film to the IGZO transistor (TFT), but also protect the active channel of the IGZO TFT from the undesired damage during the perovskite fabrication process. In order to optimize the performance of phototransistor, the different mixing ratio of PMMA:PCBM precursor was prepared and spin-coated onto the IGZO TFT. It is found that the optimum ratio for PMMA:PCBM hybrid film is 2:1, with which the phototransistor exhibits a max on/off spin-coated of
$\sim\mathbf{6}\times\mathbf{10}^{\mathbf{3}}$
. In addition, the carrier transportation property and ion blocking effect of the PMMA:PCBM interlayer are discussed.