Spatial–temporal spectroscopy characterizations and electronic structure of methylammonium perovskites

Date
2018-07-09
Authors
Liu, Zhaoyu
Bhamu, K.
Luo, Liang
Shah, Satvik
Park, Joong-Mok
Cheng, Di
Long, Men
Biswas, Rana
Fungara, F.
Shinar, Ruth
Shinar, Joseph
Vela, Javier
Wang, Jigang
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Ames Laboratory
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Physics and Astronomy
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Chemistry
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Abstract

Using time-resolved laser-scanning confocal microscopy and ultrafast optical pump/THz probe spectroscopy, we measure photoluminescence and THz-conductivity in perovskite micro-crystals and films. Photoluminescence quenching and lifetime variations occur from local heterogeneity. Ultrafast THz-spectra measure sharp quantum transitions from excitonic Rydberg states, providing weakly bound excitons with a binding energy of ~13.5 meV at low temperatures. Ab-initio electronic structure calculations give a direct band gap of 1.64 eV, a dielectric constant ~18, heavy electrons, and light holes, resulting in weakly bound excitons, consistent with the binding energies from experiment. The complementary spectroscopy and simulations reveal fundamental insights into perovskite light-matter interactions.

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This is a manuscript of an article published as Liu, Zhaoyu, K. C. Bhamu, Liang Luo, Satvik Shah, Joong-Mok Park, Di Cheng, Men Long, Rana Biswas, F. Fungara, Ruth Shinar, Joseph Shinar, Javier Vela, and Jigang Wang. "Spatial–temporal spectroscopy characterizations and electronic structure of methylammonium perovskites." MRS Communications (2018). doi: 10.1557/mrc.2018.114. Posted with permission.

Keywords
ultrafast spectroscopy, perovskites, excitonic spectra, electronic structure
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