Proceedings of 6th International Conference on Hybrid and Organic Photovoltaics (HOPV14)
Publication date: 1st March 2014
Abstract
Tandem Dye sensitised solar cells (DSSCs) are a promising modification to existing n-type DSSCs.Wherein a dye sensitised photocathode is used in place of the passive counter electrode, enabling the absorption of a broader range of photons. However the majority of high performance dyes for photocathodes absorb higher energy photons causing spectral overlap with the n-type photoanode. A series of new donor-π-acceptor dyes which absorb towards the red region of the visible spectrum (CAD 1-4)were synthesised incorporating indolinium cationic acceptorunits. Their optical and electrochemical properties have better matched energy levels for use with the triiodide redox couple in NiO-based p-type DSSCs (figure 1). NiO-based p-type DSSCs with CAD 1 and CAD 2 gave photocurrents of 3.6 and 3.3 mA cm–2 respectively, which is substantially higher than any previous red-absorbing p-DSSC dyes. These results are a significant step towards tandem DSSCs which absorb higher energy photons at the TiO2 anode and lower energy photons at the NiO cathode.
Figure 1. An energy level diagram showing the driving forces for charge injection and dye regeneration in NiO p-type DSSCs for the dyes P1, P3, and CAD 1.
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