title: Hybrid Perovskite/Perovskite Heterojunction Solar Cells.
abstract: Recently developed organic-inorganic hybrid perovskite solar cells combine low-cost fabrication and high power conversion efficiency. Advances in perovskite film optimization have led to an outstanding power conversion efficiency of more than 20%. Looking forward, shifting the focus toward new device architectures holds great potential to induce the next leap in device performance. Here, we demonstrate a perovskite/perovskite heterojunction solar cell. We developed a facile solution-based cation infiltration process to deposit layered perovskite (LPK) structures onto methylammonium lead iodide (MAPI) films. Grazing-incidence wide-angle X-ray scattering experiments were performed to gain insights into the crystallite orientation and the formation process of the perovskite bilayer. Our results show that the self-assembly of the LPK layer on top of an intact MAPI layer is accompanied by a reorganization of the perovskite interface. This leads to an enhancement of the open-circuit voltage and power conversion efficiency due to reduced recombination losses, as well as improved moisture stability in the resulting photovoltaic devices.
authors.affiliation: Department of Chemistry and Center for NanoScience (CeNS), LMU Munich , Butenandtstraße 5-13, 81377 München, Germany.
authors.forename: Yinghong
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Physik-Department, Lehrstuhl für Funktionelle Materialien, Technische Universität München , James-Franck-Straße 1, 85748 Garching, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Schlipf
authors.affiliation: Department of Materials Science, Surface Science Division, Darmstadt University of Technology , Jovanka-Bontschits-Straße 2, 64287 Darmstadt, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Wussler
authors.affiliation: Department of Chemistry and Center for NanoScience (CeNS), LMU Munich , Butenandtstraße 5-13, 81377 München, Germany.
authors.forename: Michiel L
authors.initials: ML
authors.lastname: Petrus
authors.affiliation: Department of Materials Science, Surface Science Division, Darmstadt University of Technology , Jovanka-Bontschits-Straße 2, 64287 Darmstadt, Germany.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Jaegermann
authors.affiliation: Department of Chemistry and Center for NanoScience (CeNS), LMU Munich , Butenandtstraße 5-13, 81377 München, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Bein
authors.affiliation: Physik-Department, Lehrstuhl für Funktionelle Materialien, Technische Universität München , James-Franck-Straße 1, 85748 Garching, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Müller-Buschbaum
authors.affiliation: Department of Chemistry and Center for NanoScience (CeNS), LMU Munich , Butenandtstraße 5-13, 81377 München, Germany.
authors.forename: Pablo
authors.initials: P
authors.lastname: Docampo
keywords: heterojunction; layered compound; moisture stability; perovskite; photovoltaic; solar cell