Unbalanced Hole and Electron Diffusion in Lead Bromide Perovskites.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 28240556.
- Also identified by DOI 10.1021/acs.nanolett.6b05022.
- No licence information is recorded for this record.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
We use scanning photocurrent microscopy and time-resolved microwave conductivity to measure the diffusion of holes and electrons in a series of lead bromide perovskite single crystals, APbBr<sub>3</sub>, with A = methylammonium (MA), formamidinium (FA), and Cs. We find that the diffusion length of holes (L<sub>D</sub><sup>h+</sup> ∼ 10-50 μm) is on average an order of magnitude longer than that of electrons (L<sub>D</sub><sup>e-</sup> ∼ 1-5 μm), regardless of the A-type cation or applied bias. Furthermore, we observe a weak dependence of L<sub>D</sub> across the A-cation series MA > FA > Cs. When considering the role of the halide, we find that the diffusion of holes in MAPbBr<sub>3</sub> is comparable to that in MAPbI<sub>3</sub>, but the electron diffusion length is up to five times shorter. This study shows that the disparity between hole and electron diffusion is a ubiquitous feature of lead halide perovskites. As with organic photovoltaics, this imbalance will likely become an important consideration in the optimization of lead halide perovskite solar cells.