title: Efficient luminescent solar cells based on tailored mixed-cation perovskites.
abstract: We report on a new metal halide perovskite photovoltaic cell that exhibits both very high solar-to-electric power-conversion efficiency and intense electroluminescence. We produce the perovskite films in a single step from a solution containing a mixture of FAI, PbI2, MABr, and PbBr2 (where FA stands for formamidinium cations and MA stands for methylammonium cations). Using mesoporous TiO2 and Spiro-OMeTAD as electron- and hole-specific contacts, respectively, we fabricate perovskite solar cells that achieve a maximum power-conversion efficiency of 20.8% for a PbI2/FAI molar ratio of 1.05 in the precursor solution. Rietveld analysis of x-ray diffraction data reveals that the excess PbI2 content incorporated into such a film is about 3 weight percent. Time-resolved photoluminescence decay measurements show that the small excess of PbI2 suppresses nonradiative charge carrier recombination. This in turn augments the external electroluminescence quantum efficiency to values of about 0.5%, a record for perovskite photovoltaics approaching that of the best silicon solar cells. Correspondingly, the open-circuit photovoltage reaches 1.18 V under AM 1.5 sunlight.
authors.affiliation: Laboratory of Photomolecular Science, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: Dongqin
authors.initials: D
authors.lastname: Bi
authors.affiliation: Laboratory of Photonics and Interfaces, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Tress
authors.affiliation: Laboratory of Photonics and Interfaces, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.; Group for Molecular Engineering of Functional Materials, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: M Ibrahim
authors.initials: MI
authors.lastname: Dar
authors.affiliation: Group for Molecular Engineering of Functional Materials, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: Peng
authors.identifier: http://orcid.org/0000-0002-4963-2282
authors.initials: P
authors.lastname: Gao
authors.affiliation: Laboratory of Photonics and Interfaces, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: Jingshan
authors.identifier: http://orcid.org/0000-0002-1770-7681
authors.initials: J
authors.lastname: Luo
authors.affiliation: Laboratory of Photonics and Interfaces, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: Clémentine
authors.initials: C
authors.lastname: Renevier
authors.affiliation: Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: Kurt
authors.identifier: http://orcid.org/0000-0002-9417-6634
authors.initials: K
authors.lastname: Schenk
authors.affiliation: Laboratory of Photonics and Interfaces, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: Antonio
authors.initials: A
authors.lastname: Abate
authors.affiliation: Laboratory of Photonics and Interfaces, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Giordano
authors.affiliation: Laboratory of Photomolecular Science, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: Juan-Pablo
authors.initials: JP
authors.lastname: Correa Baena
authors.affiliation: Laboratory of Photonics and Interfaces, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: Jean-David
authors.initials: JD
authors.lastname: Decoppet
authors.affiliation: Laboratory of Photonics and Interfaces, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: Shaik Mohammed
authors.initials: SM
authors.lastname: Zakeeruddin
authors.affiliation: Group for Molecular Engineering of Functional Materials, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: Mohammad Khaja
authors.identifier: http://orcid.org/0000-0001-5955-4786
authors.initials: MK
authors.lastname: Nazeeruddin
authors.affiliation: Laboratory of Photonics and Interfaces, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Grätzel
authors.affiliation: Laboratory of Photomolecular Science, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: Anders
authors.initials: A
authors.lastname: Hagfeldt
mesh_terms: D000578:Amidines / Q000737:chemistry; D017610:Calcium Compounds / Q000737:chemistry*; D002412:Cations / Q000737:chemistry*; D011211:Electric Power Supplies; D004583:Electrons; D049449:Luminescence; D010087:Oxides / Q000737:chemistry*; D012993:Solar Energy; D012996:Solutions / Q000737:chemistry; D013472:Sunlight; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D000578:Amidines; D017610:Calcium Compounds; D002412:Cations; D010087:Oxides; D012996:Solutions; C059910:perovskite; C077922:formamidine; D014025:Titanium
keywords: Applied physics; perovskites; photovoltaics; solar cells