High-Quality LaVO3Films as Solar Energy Conversion Material.
Mott insulating oxides and their heterostructures have recently been identified as potential photovoltaic materials with favorable absorption properties and an intrinsic built-in electric field that can efficiently separate excited electron-hole pairs. At the same time, they are predicted to overcome the Shockley-Queisser limit due to strong electron-electron interaction present. Despite these premises a high concentration of defects commonly observed in Mott insulating films acting as recombination centers can derogate the photovoltaic conversion efficiency. With use of the self-regulated growth kinetics in hybrid molecular beam epitaxy, this obstacle can be overcome. High-quality, stoichiometric LaVO3films were grown with defect densities of in-gap states up to 2 orders of magnitude lower compared to the films in the literature, and a factor of 3 lower than LaVO3bulk single crystals. Photoconductivity measurements revealed a significant photoresponsivity increase as high as tenfold of stoichiometric LaVO3films compared to their nonstoichiometric counterparts. This work marks a critical step toward the realization of high-performance Mott insulator solar cells beyond conventional semiconductors.
Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Hai-Tian
http://orcid.org/0000-0002-1122-8647
HT
Zhang
Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Matthew
M
Brahlek
Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Xiaoyu
http://orcid.org/0000-0003-2071-3721
X
Ji
Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Shiming
S
Lei
Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Jason
J
Lapano
Advanced Photon Source, Argonne National Laboratory , Lemont, Illinois 60439, United States.
John W
JW
Freeland
Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Venkatraman
V
Gopalan
Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Roman
R
Engel-Herbert
Mott insulator; photovoltaic materials; physical vapor deposition; thin film; transitional-metal oxide