Ultrafast Dynamics of Hole Injection and Recombination in Organometal Halide Perovskite Using Nickel Oxide as p-Type Contact Electrode

Alice Corani, Ming Hsien Li, Po Shen Shen, Peter Chen, Tzung Fang Guo, Amal El Nahhas, Kaibo Zheng, Arkady Yartsev, Villy Sundström, Carlito S. Ponseca

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45 Citations (Scopus)

Abstract

There is a mounting effort to use nickel oxide (NiO) as p-type selective electrode for organometal halide perovskite-based solar cells. Recently, an overall power conversion efficiency using this hole acceptor has reached 18%. However, ultrafast spectroscopic investigations on the mechanism of charge injection as well as recombination dynamics have yet to be studied and understood. Using time-resolved terahertz spectroscopy, we show that hole transfer is complete on the subpicosecond time scale, driven by the favorable band alignment between the valence bands of perovskite and NiO nanoparticles (NiO(np)). Recombination time between holes injected into NiO(np) and mobile electrons in the perovskite material is shown to be hundreds of picoseconds to a few nanoseconds. Because of the low conductivity of NiO(np), holes are pinned at the interface, and it is electrons that determine the recombination rate. This recombination competes with charge collection and therefore must be minimized. Doping NiO to promote higher mobility of holes is desirable in order to prevent back recombination.

Original languageEnglish
Pages (from-to)1096-1101
Number of pages6
JournalJournal of Physical Chemistry Letters
Volume7
Issue number7
DOIs
Publication statusPublished - 2016 Apr 21

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All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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