title: Mixed-organic-cation perovskite photovoltaics for enhanced solar-light harvesting.
abstract: Hybrid organic-inorganic lead halide perovskite APbX3 pigments, such as methylammonium lead iodide, have recently emerged as excellent light harvesters in solid-state mesoscopic solar cells. An important target for the further improvement of the performance of perovskite-based photovoltaics is to extend their optical-absorption onset further into the red to enhance solar-light harvesting. Herein, we show that this goal can be reached by using a mixture of formamidinium (HN=CHNH3 (+), FA) and methylammonium (CH3 NH3 (+), MA) cations in the A position of the APbI3 perovskite structure. This combination leads to an enhanced short-circuit current and thus superior devices to those based on only CH3 NH3 (+). This concept has not been applied previously in perovskite-based solar cells. It shows great potential as a versatile tool to tune the structural, electrical, and optoelectronic properties of the light-harvesting materials.
authors.affiliation: Laboratory of Photonics and Interfaces, Department of Chemistry and Chemical Engineering, Swiss Federal Institute of Technology, Station 6, 1015 Lausanne (Switzerland); Max-Planck-Institute for Solid-State Research, Heisenbergstrasse 1, 70569 Stuttgart (Germany).
authors.forename: Norman
authors.initials: N
authors.lastname: Pellet
authors.forename: Peng
authors.initials: P
authors.lastname: Gao
authors.forename: Giuliano
authors.initials: G
authors.lastname: Gregori
authors.forename: Tae-Youl
authors.initials: TY
authors.lastname: Yang
authors.forename: Mohammad K
authors.initials: MK
authors.lastname: Nazeeruddin
authors.forename: Joachim
authors.initials: J
authors.lastname: Maier
authors.forename: Michael
authors.initials: M
authors.lastname: Grätzel
keywords: energy conversion; light harvesting; organic cations; perovskite solar cells; photovoltaics