Wide bandgap perovskites are emerging as suitable candidates for the technology of tandem solar cells. Understanding their optical properties is a prerequisite for improving the corresponding solar cells’ efficiencies. In this thesis, we employ various steady-state spectroscopies to reveal the optical properties of two wide bandgap perovskites: FA0.83Cs0.17Pb(I0.7Br0.3)3 or PVK1 and FA0.83Cs0.17Pb(I0.5Br0.5)3 or PVK2. The optical properties of interest are the semiconductors’ absorption spectra, the sub-bandgap absorption features, the bandgap energy, the Urbach energy, and the excitonic binding energy. We find that the sub-bandgap absorption can be characterized by a single exponential function. We also find that the Urbach energies and the excitonic binding energies are below the thermal energy at room temperature, which signals that PVK1 and PVK2 are excellent nominees for photovoltaic absorbers. Finally, the bandgap energy is red shifted due to excitonic effects as revealed by the Elliot model.
| Date of Award | Jul 2023 |
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| Original language | English (US) |
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| Awarding Institution | - Physical Sciences and Engineering
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| Supervisor | Frédéric Laquai (Supervisor) |
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- Perovskites
- solar cells
- spectroscopy
- Urbach energy
- Elliot model