Near-infrared (NIR) dyes have diverse applications including solar cells, nonlinear optics, and bioimaging. As 50 % of the sunlight radiation energy is in the infrared region, in organic solar cells, for instance, the materials should have good light-harvesting capability not only in the UV/Vis spectral range, but also at the NIR range.

Boron dipyrromethene (BODIPY, blue in picture) is a small dye that strongly absorbs in the UV/Vis range. Jishan Wu and co-workers, National University of Singapore, have fused BODIPY with porphyrins by an intramolecular, oxidative, cyclodehydrogenation reaction. The resulting extended ring systems showed intense NIR absorption and good photostability.

With appropriate functionalization, these dyes would be suitable for solar cells and could increase their light-harvesting ability.

• BODIPY-Fused Porphyrins as Soluble and Stable Near-IR Dyes
  C. Jiao, L. Zhu, J. Wu,
  Chem. Eur. J. 2011.
  DOI: 10.1002/chem.201100619