Azulenocyanines immobilized on graphene; on the way to panchromatic absorption and efficient DSSC blocking layers
Herein, a novel electron donor-acceptor hybrid consisting of a NIR absorbing azulenocyanine as electron donor and few-layer graphene as electron acceptor was prepared. The extended aromatic core of azulenocyanine (1) assist in the exfoliation of graphite and allows formation of a very high-quality few-layer graphene azulenocyanine hybrid system (2). Formation of a stable azulenocyanine/ graphene hybrid was verified by means of an arsenal of spectroscopic and microscopic techniques. Notable is the fact that the absorption spectrum recorded for 1 and likewise that of 2 covers large portions of the solar spectrum, that is, from the UV through the visible to the NIR region. In light of the latter, we incorporated 1 as well as 2 as photosensitizer in dye sensitized solar cells (DSSCs) and probed their light harvesting. Besides an increase in the photovoltaic conversion efficiency we focused on the stability of DSSCs by preventing charge recombination between FTO and the liquid electrolyte. We used 2 as a blocking layer and in comparision with a TiCl4 pretreated blocking layer a superior conversion efficiency was realized.
- This article is part of the themed collection: Nanocarbons