Ultrafast Microscopy of Energy and Charge Transport

By Libai Huang

Department of Physics and Astronomy, Purdue University, West Lafayette, IN

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Abstract

The frontier in solar energy research now lies in learning how to integrate functional entities across multiple length scales to create optimal devices. Advancing the field requires transformative experimental tools that probe energy and charge transfer processes from the nano to the meso lengthscales. To address this challenge, we have been developing ultrafast microscopy as a new means to image multi-scale energy transport across both length and time scales, coupling simultaneous high spatial, structural, and temporal resolutions. In my talk, I will focus on our recent progress on visualization of exciton and charge transport in solar cell materials.

With simultaneous femtosecond temporal resolution and nanoscale spatial precision, we have recently revealed a singlet-mediated triplet transport mechanism in certain singlet fission materials [1]. Such new triplet exciton transport mechanism leads to favorable long-range triplet exciton diffusion on the picosecond and nanosecond timescales for solar cell applications.

We have also directly visualized hot-carrier migration in methylammonium lead iodide (CH3NH3PbI3) thin films using ultrafast microscopy approaches, demonstrating three distinct transport regimes [2]. 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.

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Researchers should cite this work as follows:

  • Libai Huang (2017), "Ultrafast Microscopy of Energy and Charge Transport," http://nanohub.org/resources/27714.

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Location

Physics, Room 203, Purdue University, West Lafayette, IN

Ultrafast Microscopy of Energy and Charge Transport
  • Ultrafast Microscopy of Energy and Charge Transport 1. Ultrafast Microscopy of Energy… 0
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  • Femtosecond (ultrafast) photography 2. Femtosecond (ultrafast) photog… 84.58458458458459
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  • Transient absorption microscopy to image motions of photogenerated carriers 3. Transient absorption microscop… 249.64964964964966
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  • Ultrafast spectroscopy of individual SWNTs 4. Ultrafast spectroscopy of indi… 501.86853520186855
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  • Exciton and charge transport 5. Exciton and charge transport 713.68034701368038
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  • Perovskite solar cells 6. Perovskite solar cells 759.22589255922594
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  • Band structure (CH3NH3PbI3) 7. Band structure (CH3NH3PbI3) 859.42609275942607
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  • Soft materials, dynamic structural disorders 8. Soft materials, dynamic struct… 1056.9903236569903
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  • Perovskites (CH3NH3PbI3) 9. Perovskites (CH3NH3PbI3) 1163.2298965632299
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  • Use two pulses to control in the space domain 10. Use two pulses to control in t… 1295.9292625959292
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  • Charge transport in perovskite thin films 11. Charge transport in perovskite… 1329.7630964297632
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  • Direct measurements of carrier diffusion 12. Direct measurements of carrier… 1354.4878211544879
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  • Hot Carriers 13. Hot Carriers 1626.4264264264266
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  • Carrier dynamics 14. Carrier dynamics 1789.4227560894228
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  • SEM 15. SEM 1850.2168835502171
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  • Hot-carrier transport 16. Hot-carrier transport 1901.3680347013681
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  • Quasi-ballistic hot-carrier transport 17. Quasi-ballistic hot-carrier tr… 2057.0570570570571
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  • Hot-carrier transport within the pulse width 18. Hot-carrier transport within t… 2152.2522522522522
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  • Carrier-phonon scattering in the first picosecond 19. Carrier-phonon scattering in t… 2240.1067734401067
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  • Hot-carrier transport 20. Hot-carrier transport 2274.4744744744744
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  • Time-dependent transport 21. Time-dependent transport 2374.8081414748081
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  • Grain boundaries 22. Grain boundaries 2454.5545545545547
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  • Defect states 23. Defect states 2506.4731398064732
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  • Defect states at boundaries 24. Defect states at boundaries 2553.8872205538873
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  • Grain boundaries and surface defects 25. Grain boundaries and surface d… 2624.4911578244914
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  • Good boundaries 26. Good boundaries 2705.6723390056723
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  • Summary — Perovskites 27. Summary — Perovskites 2765.2986319652987
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  • Acknowledgements 28. Acknowledgements 2826.0927594260929
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  • Ultrafast spectroscopy of individual SWNTs 29. Ultrafast spectroscopy of indi… 3034.7681014347681
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