title: The Interface between FTO and the TiO2 Compact Layer Can Be One of the Origins to Hysteresis in Planar Heterojunction Perovskite Solar Cells.
abstract: Organometal halide perovskite solar cells have shown rapid rise in power conversion efficiency, and therefore, they have gained enormous attention in the past few years. However, hysteretic photovoltaic characteristics, found in these solid-state devices, have been a major problem. Although it is being proposed that the ferroelectric property of perovskite causes hysteresis in the device, we observed hysteresis in a device made of nonferroelectric PbI2 as a light absorber. This result evidently supports the fact that ferroelectric property cannot be the sole reason for hysteresis. The present study investigates the roles of some key interfaces in a planar heterojunction perovskite (CH3NH3PbI(3-x)Cl(x)) solar cell that can potentially cause hysteresis. The results confirm that the interface between fluorine doped tin oxide (FTO) substrate and the TiO2 compact layer has a definite contribution to hysteresis. Although this interface is one of the origins to hysteresis, we think that other interfaces, especially the interface of the TiO2 compact layer with perovskite, can also play major roles. Nevertheless, the results indicate that hysteresis in such devices can be reduced/eliminated by changing the interlayer between FTO and perovskite.
authors.affiliation: †Toin University of Yokohama, 1614 Kurogane-cho, Aoba, Yokohama 225-8503, Kanagawa, Japan.
authors.forename: Ajay Kumar
authors.initials: AK
authors.lastname: Jena
authors.affiliation: †Toin University of Yokohama, 1614 Kurogane-cho, Aoba, Yokohama 225-8503, Kanagawa, Japan.|‡Department of Chemical Engineering, National Taiwan University, Number 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
authors.forename: Hsin-Wei
authors.initials: HW
authors.lastname: Chen
authors.affiliation: †Toin University of Yokohama, 1614 Kurogane-cho, Aoba, Yokohama 225-8503, Kanagawa, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kogo
authors.affiliation: †Toin University of Yokohama, 1614 Kurogane-cho, Aoba, Yokohama 225-8503, Kanagawa, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Sanehira
authors.affiliation: †Toin University of Yokohama, 1614 Kurogane-cho, Aoba, Yokohama 225-8503, Kanagawa, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Ikegami
authors.affiliation: †Toin University of Yokohama, 1614 Kurogane-cho, Aoba, Yokohama 225-8503, Kanagawa, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Miyasaka
keywords: PbI2; TiO2 compact layer; hysteresis; interface; perovskite solar cell; planar heterojunction