Long-range hot-carrier transport in hybrid perovskites visualized by ultrafast microscopy

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 fo...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2017-04, Vol.356 (6333), p.59-62
Main Authors: Guo, Zhi, Wan, Yan, Yang, Mengjin, Snaider, Jordan, Zhu, Kai, Huang, Libai
Format: Article
Language:English
Subjects:
Absorption
Carrier transport
Carriers
Charge transport
Cooling
Current carriers
Devices
efficiency
Grain boundaries
hot-carrier devices
hybrid perovskites
Iodides
Kinetic energy
Kinetics
Lead
MATERIALS SCIENCE
Metal halides
Microscopy
Nanostructure
Perovskites
Photovoltaic cells
Solar cells
SOLAR ENERGY
Thin films
Transport
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Summary: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.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.aam7744