Dye-sensitized solar cells (DSSC) have attracted considerable attention in recent years as they offer the possibility of low-cost conversion of photovoltaic energy This Review focuses on recent advances in molecular design and technological aspects of metal-free organic dyes for applications in dye-sensitized solar cells Special attention has been paid to the design principles of these dyes and on the effect of various electrolyte systems Cosensitization, an emerging technique to extend the absorption range, is also discussed as a way to improve the performance of the device In addition, we report on inverted dyes for photocathodes, which constitutes a relatively new approach for the production of tandem cells Special consideration has been paid to the correlation between the molecular structure and physical properties to their performance in DSSCs

Metal-Free Organic Dyes for Dye-Sensitized Solar Cells: From Structure: Property Relationships to Design Rules

J-aggregates are of significant interest for organic materials conceived by supramolecular approaches. Their discovery in the 1930s represents one of the most important milestones in dye chemistry as well as the germination of supramolecular chemistry. The intriguing optical properties of J-aggregates (in particular, very narrow red-shifted absorption bands with respect to those of the monomer and their ability to delocalize and migrate excitons) as well as their prospect for applications have motivated scientists to become involved in this field, and numerous contributions have been published. This Review provides an overview on the J-aggregates of a broad variety of dyes (including cyanines, porphyrins, phthalocyanines, and perylene bisimides) created by using supramolecular construction principles, and discusses their optical and photophysical properties as well as their potential applications. Thus, this Review is intended to be of interest to the supramolecular, photochemistry, and materials science communities.

J-aggregates: from serendipitous discovery to supramolecular engineering of functional dye materials.

The nonradiative conversion of light energy into heat (photothermal therapy, PTT) or sound energy (photoacoustic imaging, PAI) has been intensively investigated for the treatment and diagnosis of cancer, respectively. By taking advantage of nanocarriers, both imaging and therapeutic functions together with enhanced tumour accumulation have been thoroughly studied to improve the pre-clinical efficiency of PAI and PTT. In this review, we first summarize the development of inorganic and organic nano photothermal transduction agents (PTAs) and strategies for improving the PTT outcomes, including applying appropriate laser dosage, guiding the treatment via imaging techniques, developing PTAs with absorption in the second NIR window, increasing photothermal conversion efficiency (PCE), and also increasing the accumulation of PTAs in tumours. Second, we introduce the advantages of combining PTT with other therapies in cancer treatment. Third, the emerging applications of PAI in cancer-related research are exemplified. Finally, the perspectives and challenges of PTT and PAI for combating cancer, especially regarding their clinical translation, are discussed. We believe that PTT and PAI having noteworthy features would become promising next-generation non-invasive cancer theranostic techniques and improve our ability to combat cancers.

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Photothermal therapy and photoacoustic imaging via nanotheranostics in fighting cancer

The long wavelength (far-red to NIR) analyte-responsive fluorescent probes are advantageous for in vivo bioimaging because of minimum photo-damage to biological samples, deep tissue penetration, and minimum interference from background auto-fluorescence by biomolecules in the living systems. Thus, great interest in the development of new long wavelength analyte-responsive fluorescent probes has emerged in recent years. This review highlights the advances in the development of far-red to NIR fluorescent probes since 2000, and the probes are classified according to their organic dye platforms into various categories, including cyanines, rhodamine analogues, BODIPYs, squaraines, and other types (240 references).

Far-red to near infrared analyte-responsive fluorescent probes based on organic fluorophore platforms for fluorescence imaging

Cyanines during the 1990s: A Review

Nitrogen‐, and/or Sulfur-Containing Heterocyclic Rings Poulomi Majumdar,†,‡ Anita Pati,†,§ Manabendra Patra, Rajani Kanta Behera,† and Ajaya Kumar Behera*,† †Organic Synthesis Laboratory, School of Chemistry, Sambalpur University, Jyoti Vihar, Burla 768019, Orissa, India ‡State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, P.R. China School of Applied Sciences (Chemistry), KIIT University, Bhubaneswar 751024, India National Institute of Science & Technology, Palur Hill, Berhampur 761068, Orissa, India

Acid hydrazides, potent reagents for synthesis of oxygen-, nitrogen-, and/or sulfur-containing heterocyclic rings.

A synthon approach to spiro compounds

Cationic dyes are known to interact with membranes and, therefore, are used as membrane probes. The alkyl chains of the dyes play a role in modifying the environment of the chromophore and affect the nature of interaction with the micelle. A number of cationic dyes with varying alkyl chains (C 1 to C 18 ) have been synthesized and their interaction with sodium dodecyl sulfate (SDS) is reported. From the absorption, fluorescence spectra and binding constant values it has been proposed that: (a) C 1 –C 8 dyes solubilize in the micelle and the chromophore occupies a methanolic/ethanolic environment, (b) C 10 –C 14 dyes exist both as an extended monomer and as folded species in presence of SDS, which is reflected in two Gaussian peaks, (c) the experimentally obtained absorption spectra for C 16 and C 18 dyes can be explained by three Gaussian peaks due to monomer ⇋ dimer in the absence of surfactant and two such peaks due to monomer and folded monomer in the presence of surfactants. The binding constant and fluorescence intensity values support this proposition.

Dye–surfactant interaction: chain folding during solubilization of styryl pyridinium dyes in sodium dodecyl sulfate aggregates

Interaction of a series of N -alkyl styryl pyridinium dyes having varied alkyl chain (C n ) with nonionic surfactant (Triton X-100) solution has been studied by using absorption and emission techniques. The binding constants of the dyes (C 1 –C 18 ) with the surfactant aggregates have been calculated and found to increase with increasing alkyl chain length of the dyes. A decrease in the CMC value of TX-100 in presence of the dyes with increasing chain length has been observed and the phenomenon is attributed to the increasing hydrophobicity of the additive. The relative E T (30) values of the local environment of the dyes in TX-100 micelles with respect to standard solvents have been determined. A solubilisation strategy of the micelle for the dyes has been reported where the cationic head group remains in the oxyethylene cage of the micelle and the hydrophobic tail remains buried in the micellar core due to pulling effect.

Rajani K. Behera

Papers

Cyanines during the 1990s: A Review

Acid hydrazides, potent reagents for synthesis of oxygen-, nitrogen-, and/or sulfur-containing heterocyclic rings.

A synthon approach to spiro compounds

Dye–surfactant interaction: chain folding during solubilization of styryl pyridinium dyes in sodium dodecyl sulfate aggregates

Interaction of N-alkyl styryl pyridinium dyes with TX-100 in aqueous medium : Role of the alkyl chain during solubilisation