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- Title
The importance of relativistic effects on two-photon absorption spectra in metal halide perovskites.
- Authors
Wei, Zimu; Guo, Dengyang; Thieme, Jos; Katan, Claudine; Caselli, Valentina M.; Even, Jacky; Savenije, Tom J.
- Abstract
Despite intense research into the optoelectronic properties of metal halide perovskites (MHPs), sub-bandgap absorption in MHPs remains largely unexplored. Here we recorded two-photon absorption spectra of MHPs using the time-resolved microwave conductivity technique. A two-step upward trend is observed in the two-photon absorption spectrum for methylammonium lead iodide, and some analogues, which implies that the commonly used scaling law is not applicable to MHPs. This aspect is further confirmed by temperature-dependent conductivity measurements. Using an empirical multiband tight binding model, spectra for methylammonium lead iodide were calculated by integration over the entire Brillouin zone, showing compelling similarity with experimental results. We conclude that the second upward trend in the two-photon absorption spectrum originates from additional optical transitions to the heavy and light electron bands formed by the strong spin-orbit coupling. Hence, valuable insight can be obtained in the opto-electronic properties of MHPs by sub-bandgap spectroscopy, complemented by modelling. Metal halide perovskites possess interesting properties but their sub-bandgap absorption remains largely unexplored. Here Wei et al. employ two-photon absorption spectroscopy with time-resolved microwave conductivity technique to confirm the existence of strong spin-orbit coupling effect.
- Subjects
RELATIVISTIC effects in atoms; LIGHT absorption; ABSORPTION spectra; METAL halides; METHYLAMMONIUM
- Publication
Nature Communications, 2019, Vol 10, Issue 1, pN.PAG
- ISSN
2041-1723
- Publication type
Article
- DOI
10.1038/s41467-019-13136-y