| Autor: |
Paraecattil, Arun Aby, De Jonghe-Risse, Jelissa, Pranculis, Vytenis, Teuscher, Joël, Moser, Jacques-E. |
| Zdroj: |
The Journal of Physical Chemistry - Part C; September 2016, Vol. 120 Issue: 35 p19595-19602, 8p |
| Abstrakt: |
Applying time-resolved electroabsorption spectroscopy for the first time to methylammonium lead triiodide perovskite (MAPbI3) thin films under reverse bias, we monitored optically the ultrafast evolution of the local counter-electric field produced by the drift of photogenerated electrons and holes in opposite directions. Under an externally applied electric field of |E| < 105V cm–1, the carriers were found to reach a separation of 40 nm within ∼1 ps. This distance corresponds to the average dimensions of crystalline grains in the active film, at the boundaries of which charges were trapped. An intragrain average carrier drift mobility of μ±= 23 cm2V–1s–1was inferred. Subsequent charge detrapping, migration through the entire film, and accumulation at its insulated surfaces caused a blue shift of the perovskite absorption edge that arose within tens of picoseconds, owing to a trap-limited electron drift mobility μn= 6 cm2V–1s–1. Charge recombination was entirely suppressed between field-separated photocarriers generated at initial densities of n0≤ 2 × 1016cm–3. Accumulation of electrons at the interface between a mesoporous TiO2electron-transport layer and a multigrain MAPbI3film was also observed, which was indicative of delayed charge injection through a poor contact junction. |
| Databáze: |
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