Chlorophylls as Molecular Semiconductors: Introduction and State of Art

Abstract

Chlorophylls (Chls) and their derivatives are the most common pigments used for light absorption, energy transfer, and charge separation in photosynthetic organisms. Their functions change upon different aggregation states and specific pigment–protein interactions. Differences in the aromatic π‐system and substituents finely tune Chls electronic, spectroscopic, and supramolecular characteristics. The varieties of Chls species and the possibility of chemical manipulation, together with their exceptional absorption cross section, make them attractive materials for applications as sensitizer in energy conversion devices. Moreover, when deposited as thin films, Chls and their semi‐synthetic derivatives exhibit the typical behavior of molecular organic semiconductors with good charge carrier mobility and Fermi level suitable for their use in optoelectronic devices like phototransistors. This review aims at bridging the possible knowledge and language gap between biochemists and biophysicists working on Chls, and material scientists developing organic optoelectronic devices. Starting from the structural features, and proceeding towards optoelectronic devices, the review offers a critical overview on the uses of Chls as light‐responsive molecular semiconductors known so far. Exploiting the high efficiency of these renewable, biocompatible, and recyclable natural systems can pave the way for next generation biooptoelectronics, including artificial light energy converters, photodetectors, and, more in general, forward‐thinking technologies.

Engineered Living Hydrogels

“…[218] In addition, photosynthetic microorganisms can harvest solar energy to produce electricity, [219] and thus enable a series of optoelectronic devices such as phototransistors, photodetectors, and photovoltaics. [220] Engineered living hydrogels with electroactive microbial cells (i.e., exoelectrogens) can generate electrical energy from chemical energy. [221] Exoelectrogens such as S. oneidensis and Geobacter species consume chemical energy in organic waste and renewable biomass and produce electrons (Figure 13b).…”

Charge Transfer as Bridging Correlator for DSSC Efficiency and NLO Property

“…Charge transfer (CT) plays an important role in organic molecules used in non-linear optics (NLO), [1][2][3][4][5] dye-sensitized solar cells (DSSCs), [6][7][8][9][10][11][12][13][14] sensing, [15,16] semiconductors, [17] and organic light-emitting diodes (OLEDs). [18] For an organic chromophore to show better CT properties, it must have a push-pull (Donor-π -Acceptor) framework.…”

Biopolymer Films of Metal-Coordinated Chlorophyll-a Derivatives for “Green” Supercapacitor Electrodes

“…Chlorophylls (Chls) are the most abundant cyclic-tetrapyrrole dye molecules in nature, and they act as the key materials in natural photosynthesis. Chls could be extensively extracted from natural higher plants or cultured photosynthetic bacteria, and many derivatives have been developed aiming at the applications to solar energy utilization as well as in the field of medicinal chemistry. − Exceptional merits such as abundant resources, non-toxicity, and sustainability have been stimulating scientists to develop Chl derivatives as functional materials. − …”