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

详细信息    查看全文

• 作者：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 Jr.
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：April 7, 2016
• 年：2016
• 卷：7
• 期：7
• 页码：1096-1101
• 全文大小：357K
• ISSN：1948-7185

文摘

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.