Ultra Long-Lived Electron-Hole Separation within Water-Soluble Colloidal ZnO Nanocrystals: Prospective Applications for Solar Energy Production

Anna M. Cieślak,^a Mariia V. Pavliuk,^b Luca D’Amario,^b Mohamed Abdellah,^b Kamil Sokołowski,^a Urszula Rybinska,^b Daniel L.A. Fernandes,^b Michał K. Leszczyński,^a Fikret Mamedov,^b Ahmed M. El-Zhory,^b Jens Föhlinger,^b Alena Budinská,^b Małgorzata Wolska-Pietkiewicz,^c Leif Hammarström,^b Janusz Lewińskia^a,c Jacinto Sá^a,b
a Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw 01-224, Poland
^b Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala 75120, Sweden
^c Faculty of Chemistry, Warsaw University of Technology, Warsaw 00-661, Poland

DOI: 10.1016/j.nanoen.2016.09.045
First published online 28 Sep 2016.
Paper on the publisher's website.

Zinc oxide was one of the first semiconductors used in dye-sensitized solar cells but its instability in aqueous media precludes its use for large-scale applications. Herein, we report on a novel ZnO nanocrystal material derived by an organometallic approach that is simultaneously stable and soluble in water due to its carboxylate oligoethylene glycol shell strongly anchored to the inorganic core by the head groups. The resulting unique inorganic core-organic shell interface also stabilizes the photo-generated hole, leading to a dramatic slowing down of charge recombination, which otherwise is a major hurdle in using nanostructured ZnO.