title: Long-range hot-carrier transport in hybrid perovskites visualized by ultrafast microscopy.
abstract: The Shockley-Queisser limit for solar cell efficiency can be overcome if hot carriers can be harvested before they thermalize. Recently, carrier cooling time up to 100 picoseconds was observed in hybrid perovskites, but it is unclear whether these long-lived hot carriers can migrate long distance for efficient collection. We report direct visualization of hot-carrier migration in methylammonium lead iodide (CH3NH3PbI3) thin films by ultrafast transient absorption microscopy, demonstrating three distinct transport regimes. Quasiballistic transport was observed to correlate with excess kinetic energy, resulting in up to 230 nanometers transport distance that could overcome grain boundaries. The nonequilibrium transport persisted over tens of picoseconds and ~600 nanometers before reaching the diffusive transport limit. These results suggest potential applications of hot-carrier devices based on hybrid perovskites.
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Zhi
authors.identifier: 0000-0003-3990-3189
authors.initials: Z
authors.lastname: Guo
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Yan
authors.identifier: 0000-0003-4618-4960
authors.initials: Y
authors.lastname: Wan
authors.affiliation: National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA.
authors.forename: Mengjin
authors.initials: M
authors.lastname: Yang
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Jordan
authors.identifier: 0000-0002-8754-6270
authors.initials: J
authors.lastname: Snaider
authors.affiliation: National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA.
authors.forename: Kai
authors.identifier: 0000-0003-0908-3909
authors.initials: K
authors.lastname: Zhu
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA. libai-huang@purdue.edu.
authors.forename: Libai
authors.identifier: 0000-0001-9975-3624
authors.initials: L
authors.lastname: Huang