Hot carrier extraction in CH3NH3PbI3 unveiled by pump-push-probe spectroscopy

Swee Sien Lim*, David Giovanni, Qiannan Zhang, Ankur Solanki, Nur Fadilah Jamaludin, Jia Wei Melvin Lim, Nripan Mathews, Subodh Mhaisalkar, Maxim S. Pshenichnikov, Tze Chien Sum

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Halide perovskites are promising materials for development in hot carrier (HC) solar cells, where the excess energy of above-bandgap photons is harvested before being wasted as heat to enhance device efficiency. Presently, HC separation and transfer processes at higher-energy states remain poorly understood. Here, we investigate the excited state dynamics in CH3NH3PbI3 using pump-push-probe spectroscopy. It has its intrinsic advantages for studying these dynamics over conventional transient spectroscopy, albeit complementary to one another. By exploiting the broad excited-state absorption characteristics, our findings reveal the transfer of HCs from these higher-energy states into bathophenanthroline (bphen), an energy selective organic acceptor far above perovskite's band edges. Complete HC extraction is realized only after overcoming the interfacial barrier formed at the heterojunction, estimated to be between 1.01 and 1.08 eV above bphen's lowest unoccupied molecular orbital level. The insights gained here are essential for the development of a new class of optoelectronics.

Original languageEnglish
Article number3620
Number of pages6
JournalScience Advances
Volume5
Issue number11
DOIs
Publication statusPublished - Nov-2019

Keywords

  • PEROVSKITE
  • EFFICIENCY
  • TRANSPORT
  • DYNAMICS
  • ENERGY

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