title: Acoustic-optical phonon up-conversion and hot-phonon bottleneck in lead-halide perovskites.
abstract: The hot-phonon bottleneck effect in lead-halide perovskites (APbX3) prolongs the cooling period of hot charge carriers, an effect that could be used in the next-generation photovoltaics devices. Using ultrafast optical characterization and first-principle calculations, four kinds of lead-halide perovskites (A=FA+/MA+/Cs+, X=I-/Br-) are compared in this study to reveal the carrier-phonon dynamics within. Here we show a stronger phonon bottleneck effect in hybrid perovskites than in their inorganic counterparts. Compared with the caesium-based system, a 10 times slower carrier-phonon relaxation rate is observed in FAPbI3. The up-conversion of low-energy phonons is proposed to be responsible for the bottleneck effect. The presence of organic cations introduces overlapping phonon branches and facilitates the up-transition of low-energy modes. The blocking of phonon propagation associated with an ultralow thermal conductivity of the material also increases the overall up-conversion efficiency. This result also suggests a new and general method for achieving long-lived hot carriers in materials.
authors.affiliation: Australian Centre for Advanced Photovoltaics, School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Yang
authors.affiliation: Australian Centre for Advanced Photovoltaics, School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.|Centre for Micro-Photonics, Swinburne University of Technology, Melbourne, Victoria 3122, Australia.
authors.forename: Xiaoming
authors.identifier: 0000-0001-8298-483X
authors.initials: X
authors.lastname: Wen
authors.affiliation: Australian Centre for Advanced Photovoltaics, School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: Hongze
authors.initials: H
authors.lastname: Xia
authors.affiliation: Australian Centre for Advanced Photovoltaics, School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: Rui
authors.initials: R
authors.lastname: Sheng
authors.affiliation: Australian Centre for Advanced Photovoltaics, School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: Qingshan
authors.initials: Q
authors.lastname: Ma
authors.affiliation: Australian Centre for Advanced Photovoltaics, School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: Jincheol
authors.identifier: 0000-0001-7374-2740
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Chemistry, The University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Patrick
authors.identifier: 0000-0002-2359-1304
authors.initials: P
authors.lastname: Tapping
authors.affiliation: Department of Chemistry, The University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Harada
authors.affiliation: Department of Chemistry, The University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Tak W
authors.initials: TW
authors.lastname: Kee
authors.affiliation: State Key Lab of Advanced Technologies for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China.
authors.forename: Fuzhi
authors.initials: F
authors.lastname: Huang
authors.affiliation: Department of Materials Science and Engineering, Monash University, Melbourne, Victoria 3800, Australia.
authors.forename: Yi-Bing
authors.initials: YB
authors.lastname: Cheng
authors.affiliation: Australian Centre for Advanced Photovoltaics, School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: Martin
authors.initials: M
authors.lastname: Green
authors.affiliation: Australian Centre for Advanced Photovoltaics, School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: Anita
authors.identifier: 0000-0001-9849-4755
authors.initials: A
authors.lastname: Ho-Baillie
authors.affiliation: Australian Centre for Advanced Photovoltaics, School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: Shujuan
authors.initials: S
authors.lastname: Huang
authors.affiliation: Australian Centre for Advanced Photovoltaics, School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: Santosh
authors.initials: S
authors.lastname: Shrestha
authors.affiliation: Australian Centre for Advanced Photovoltaics, School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: Robert
authors.initials: R
authors.lastname: Patterson
authors.affiliation: Australian Centre for Advanced Photovoltaics, School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: Gavin
authors.initials: G
authors.lastname: Conibeer