Near‐Infrared Organic Compounds and Emerging Applications

Abstract

This Focus Review describes the emerging class of near-infrared (NIR) organic compounds containing the conjugated polyene, polymethine, and donor-acceptor chromophores and exploration of their NIR-absorbing, NIR-fluorescence, and NIR-photosensitizing properties for potential applications in heat absorbers, solar cells, and NIR light-emitting diodes. Examples of NIR organic compounds are reviewed with emphasis on the molecular design, NIR absorption, and fluorescence and particular emerging applications. The donor-acceptor type of NIR chromophores are particularly introduced owing to some unique features, including the designer-made energy gaps, facile synthesis, good processability, and controllable morphology and properties in the solid state. Future directions in research and development of NIR organic materials and applications are then offered from a personal perspective.

Interpreting the near-infrared reflectance of a series of perylene pigments

“…These results also demonstrate that a significant lowering of the HOMO-LUMO gap could lead to increased NIR-absorption [3], [26].…”

“…1a) have made them suitable for a wide variety of applications including, electro-photographic photoreceptors, light-emitting diodes, field-effect transistors, solar cells and other optoelectronic photonic devices [3]. The key to the optoelectronic characteristics of perylene is the conjugated π-system of the polycyclic aromatic structure (Fig.…”

Thionated perylene diimides with intense absorbance in the near-IR

“…8 Currently many of the materials being investigated for these applications absorb in the UV/visible region, however, as 50% of solar energy falls in the near infrared (NIR) spectral range, the efficiency of these devices could be greatly improved by extending the absorption of these materials to 750 nm and beyond. 9 To date, NIR absorbance of rylene dyes has been achieved by extension of the perylene core along the longer 10 or shorter 11 axis of the molecule, by deprotonation 12,13 or via the formation of J-aggregates.…”

UV—vis spectroscopy of the coupling products of the palladium-catalyzed C—H arylation of the BODIPY core

“…14 Attaching suitably chosen substituents at the right positions of the BODIPY core can lead to bathochromically shifted absorption and emission spectra, even reaching the near-infrared (NIR) spectral region, which makes these fluorophores more useful materials, especially in bioscience. The range of applications is broad and comprises biological labels and probes, 2,15 fluorescent indicators, 16 organic light emitting diodes, 17 laser dyes, 18,19 potential photosensitizers in photodynamic therapy, 20 energy transfer cassettes 19,21 and dye-sensitized solar cells. 19,22 In this report, we describe the UV-vis spectroscopy of a set of 3-aryl and 3,5-diaryl-4,4-difluoro-4-bora-3a,4a-diaza-sindacene dyes (1-15, Chart 1), synthesized via the novel, direct, palladium-catalyzed C-H (het)arylation reaction of the BODIPY core.…”