Description
- Abstract:
- Perovskite solar cells have attracted considerable attention in recent years due to their rapidly increasing power conversion efficiency, which currently exceeds 24%. Despite this success achieved through improvements in the fabrication processes and compositional engineering, the underlying optoelectronic properties of these materials, including charge transport, remain controversial. Here we studied carrier transport in perovskite materials using two related photoluminescence spectroscopy methods. First, we developed a time-resolved photoluminescence imaging method for studying carrier diffusion in formamidinium lead triiodide (FAPbI3) perovskite thin films. With this method, it was found that carrier diffusivity increases when background carriers are present. This effect may be explained by trap-carrier interactions. Second, a steady state photoluminescence method was developed to study carrier diffusion. In particular it was used to study carrier transport barriers and help identify sub-grain special boundaries in FAPbI3 perovskite thin films. Interestingly, these boundaries which restrict carrier diffusion and serve as nonradiative recombination sites, cannot be observed by conventional AFM or SEM measurements. The presence of such boundaries may explain why the performance of perovskite solar cells has not scaled with apparent grain size. With this same method, carrier transport across ferroelastic twin boundaries (FTB) was studied in methylammonium lead triiodide (MAPbI3) single crystals. It was found that FTBs have little effect on carrier transport and recombination, this in contrast both to normal grain boundaries and special subgrain boundaries.
- Notes:
- Thesis (Ph. D.)--Brown University, 2019
Access Conditions
- Rights
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- Restrictions on Use
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Citation
Li, Wenhao,
"Direct Optical Characterization of Carrier Transport and Structural Properties in Halide Perovskite Materials"
(2019).
Physics Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://repository.library.brown.edu/studio/item/bdr:1129472/
