Metallopolyyne Polymers as New Functional Materials for Photovoltaic and Solar Cell Applications

Platinum-Acetylide Complexes as Nonfullerene Acceptors in Organic Photovoltaic Systems

Three distinct n-type semiconductors were derived from a platinum-trialkyl phosphine complex; to lower their LUMO levels, various indene derivatives were incorporated using thiophene (PtTIC (1)), thieno[3,2-b]thiophene (PtT2IC (2)), and 4H-cyclopenta[2,1-b:3,4-b']dithiophene (PtCDTIC (3)) as the acetylide donor units. Single-crystal X-ray diffractometry analysis revealed translinear platinum-acetylide complexation in all cases. The strong (═O···S) interactions between the oxygen atoms of the indene acceptor units and the sulfur atoms of the thiophene-derived donor units induced a highly planar orientation among the heterocyclic ligands, featuring π-π interactions between the planes. Platinum complexes 1, 2, and 3 exhibited strong absorption in the 500-800 nm range, resulting from efficient intramolecular charge transfer transitions from the central platinum-containing donor unit to the terminal acceptors, as well as unique emission in the near-infrared region owing to the heavy-atom effect. The ultraviolet photoelectron spectroscopy results indicated that the LUMO levels were comparable to those of typical nonfullerene acceptors (NFAs). The n-type semiconductors comprising 1, 2, and 3 as NFAs exhibited photoelectric conversion properties in the corresponding organic photovoltaics. The highest conversion efficiency (3.0%) was attained by complex 3.

Polymers Containing Phenothiazine, Either as a Dopant or as Part of Their Structure, for Dye-Sensitized and Bulk Heterojunction Solar Cells

Potential photovoltaic technology includes the newly developed dye-sensitized solar cells (DSSCs) and bulk heterojunction (BHJ) solar cells. Owing to their diverse qualities, polymers can be employed in third-generation photovoltaic cells to specifically alter their device elements and frameworks. Polymers containing phenothiazine, either as a part of their structure or as a dopant, are easy and economical to synthesize, are soluble in common organic solvents, and have the potential to acquire desired electrochemical and photophysical properties by mere tuning of their chemical structures. Such polymers have therefore been used either as photosensitizers in dye-sensitized solar cells, where they have produced power conversion efficiency (PCE) values as high as 5.30%, or as donor or acceptor materials in bulk heterojunction solar cells. Furthermore, they have been employed to prepare liquid-free polymer electrolytes for dye-sensitized and bulk heterojunction solar cells, producing a PCE of 8.5% in the case of DSSCs. This paper reviews and analyzes almost all research works published to date on phenothiazine-based polymers and their uses in dye-sensitized and bulk heterojunction solar cells. The impacts of their structure and molecular weight and the amount when used as a dopant in other polymers on the absorption, photoluminescence, energy levels of frontier orbitals, and, finally, photovoltaic parameters are reviewed. The advantages of phenothiazine polymers for solar cells, the difficulties in their actual implementation and potential remedies are also evaluated.

Facile Mechanochemical Approach To Synthesizing Edible Food Preservation Coatings Based On Alginate/Ascorbic Acid-Layered Double Hydroxide Bio-Nanohybrids

A bionanohybrid based on ascorbic acid-intercalated layered double hydroxides (LDHs) was synthesized using a facile and novel mechanochemical grinding technique, and its efficacy as an edible food coating is reported. Ascorbic acid-intercalated Mg-Al-LDHs (AA-LDHs) are synthesized using a green water-assisted grinding approach. The successful synthesis of the mechanochemically ground AA-LDHs was confirmed by the shifts observed in the basal peaks of the LDHs based on a powder X-ray diffraction, changes in the positions of vibrational frequencies of ascorbic acid based on Fourier Transform Infrared Spectroscopy, and significant changes in the intensity and peak positions of the core-shell bands based on X-ray photoelectron spectroscopy. The resulting nanohybrid further demonstrates thermal stability in thermogravimetric and derivative thermogravimetric analysis. Transmission electron microscopy images of the mechanochemically synthesized AA-LDHs reveal a plate-like morphology, which is a characteristic of the hydrotalcite-like structure. In a novel application, an edible coating was prepared by blending the AA-LDHs into a biocompatible alginate matrix, and the coating was developed on freshly plucked strawberries using the dip-coating method. In order to evaluate the efficacy of the coating, the total phenolic content, pH, microbial growth, weight loss, titratable acidity, and ascorbic acid content were monitored in the coated and uncoated fruits for a period of 18 days. The results reveal that the shelf life of strawberries increases from 9 days to 15 days for the nanohybrid coated fruits, suggesting the potential food preservation applications of the nanohybrid.

The role of CT excitations in PDI aggregates

Energies and couplings of local excitations and charge transfer states control the nature of singlets and triplets in PDI aggregates.

Limitations and Perspectives on Triplet-Material-Based Organic Photovoltaic Devices

Organic photovoltaic cells (OPVs) have attracted broad attention and become a very energetic field after the emergence of nonfullerene acceptors. Long-lifetime triplet excitons are expected to be good candidates for efficiently harvesting a photocurrent. Parallel with the development of OPVs based on singlet materials (S-OPVs), the potential of triplet materials as photoactive layers has been explored. However, so far, OPVs employing triplet materials in a bulk heterojunction have not exhibited better performance than S-OPVs. Here, the recent progress of representative OPVs based on triplet materials (T-OPVs) is briefly summarized. Based on that, the performance limitations of T-OPVs are analyzed. The shortage of desired triplet materials with favorable optoelectronic properties for OPVs, the tradeoff between long lifetime and high binding energy of triplet excitons, as well as the low charge mobility in most triplet materials are crucial issues restraining the efficiencies of T-OPVs. To overcome these limitations, first, novel materials with desired optoelectronic properties are urgently demanded; second, systematic investigation on the contribution and dynamics of triplet excitons in T-OPVs is necessary; third, close multidisciplinary collaboration is required, as proved by the development of S-OPVs.

Rise of Conjugated Poly-ynes and Poly(Metalla-ynes): From Design Through Synthesis to Structure-Property Relationships and Applications

Conjugated poly-ynes and poly(metalla-ynes) constitute an important class of new materials with potential application in various domains of science. The key factors responsible for the diverse usage of these materials is their intriguing and tunable chemical and photophysical properties. This review highlights fascinating advances made in the field of conjugated organic poly-ynes and poly(metalla-ynes) incorporating group 4-11 metals. This includes several important aspects of conjugated poly-ynes viz. synthetic protocols, bonding, electronic structure, nature of luminescence, structure-property relationships, diverse applications, and concluding remarks. Furthermore, we delineated the future directions and challenges in this particular area of research.

Phosphorescent platinum(ii) alkynyls end-capped with benzothiazole units

Phosphorescent platinum(ii) alkynyls. Phosphorescent trans-bis(alkynyl) bis(phosphine) or bis(cyanide) Pt^II derivatives (1–4) based on the 2-phenylbenzothiazole unit have been prepared. The negative solvatochromic behavior of 4 has been analyzed by the Kamlet–Taft solvent scale and the Gutmann's acceptor numbers. The optical properties were addressed by TD and DFT calculations on 2 and 4.

A "roller-wheel" Pt-containing small molecule that outperforms its polymer analogs in organic solar cells

A novel Pt-bisacetylide small molecule (Pt-SM) featuring "roller-wheel" geometry was synthesized and characterized. When compared with conventional Pt-containing polymers and small molecules having "dumbbell" shaped structures, Pt-SM displays enhanced crystallinity and intermolecular π-π interactions, as well as favorable panchromatic absorption behaviors. Organic solar cells (OSCs) employing Pt-SM achieve power conversion efficiencies (PCEs) up to 5.9%, the highest reported so far for Pt-containing polymers and small molecules.

Synthesis and characterization of metallo-supramolecular polymers

The incorporation of metal centers into the backbone of polymers has led to the development of a broad range of organometallic and coordination compounds featuring properties that are relevant for potential applications in diverse areas of research, ranging from energy storage/conversion to bioactive or self-healing materials. In this review, the basic concepts and synthetic strategies leading to these types of materials as well as the scope of available characterization techniques will be summarized and discussed.

Synthesis of platinum-containing poly(phenyleneethynylene)s having various chromophores: aggregation and optical properties

Various platinum-containing phenylene–ethynylene–arylene polymers were synthesized, and the relationships between the optical properties and aggregation behaviour were examined.

Synthesis, characterization, photophysics, and anion binding properties of platinum(ii) acetylide complexes with urea group

The relationship between the structure and anion-binding ability of platinum(ii) acetylide complexes with urea group has been studied.

Metallopolymers for energy production, storage and conservation

In this review, we explore the recent advances of using metallopolymers in organic solar cells, white organic light-emitting diodes and lithium-ion batteries. The structure–property relationship of these polymers and their device performances are discussed.

Metal-metal quadruple bonds supported by 5-ethynylthiophene-2-carboxylato ligands: preparation, molecular and electronic structures, photoexcited state dynamics, and application as molecular synthons

From the reaction between M2(T(i)PB)4 and 2 equiv of 5-ethynylthiophene-2-carboxylic acid (H-ThCCH) in toluene, the complexes trans-M2(T(i)PB)2(ThCCH)2, where M = Mo (I) or W (II) and T(i)PB = 2,4,6-triisopropyl benzoate, have been isolated and characterized by (1)H NMR, IR, MALDI-TOF MS, UV-vis, steady-state emission, transient absorption, and time-resolved infrared (TRIR) spectroscopies and single-crystal X-ray crystallography for I. The molecular structure of I confirms the trans-substitution pattern and the extended conjugation of the ethynylthienyl ligands via interaction with the Mo2δ orbital. The HOMO of both I and II is the M2δ orbital, and the intense color of the compounds (I is red and II is blue) is due to the M2δ-to-ThCCH (1)MLCT transition. The S1 states for I and II are (1)MLCT. The T1 state is (3)MLCT for II, but (3)MoMoδδ* for I. The TRIR spectra of the ν(C≡C) stretch in the MLCT states are consistent with the delocalization of the electron over both ThCCH ligands. Compound I is shown to be a synthon for the preparation of trans-Mo2(T(i)PB)2(ThCCPh)2 (III) and trans-Mo2(T(i)PB)2(ThCCAuPPh3)2 (IV). Both III and IV have been characterized spectroscopically and by single-crystal X-ray diffraction. The structure of III indicates the extended π-conjugation of the trans-ethynyl-thienyl units extends to the added phenyl rings.

Metal‐Containing Polymers

The article provides an overview of the synthesis, properties, and applications of metal‐containing polymers. The past decade has shown an exponential increase in synthetic methods, resulting in metal‐containing polymers, their characterization techniques, and their potential application into a variety of fields, including chemistry, medicine, biotechnology, and more.

Small molecule organic semiconductors on the move: promises for future solar energy technology

This article is written from an organic chemist's point of view and provides an up-to-date review about organic solar cells based on small molecules or oligomers as absorbers and in detail deals with devices that incorporate planar-heterojunctions (PHJ) and bulk heterojunctions (BHJ) between a donor (p-type semiconductor) and an acceptor (n-type semiconductor) material. The article pays particular attention to the design and development of molecular materials and their performance in corresponding devices. In recent years, a substantial amount of both, academic and industrial research, has been directed towards organic solar cells, in an effort to develop new materials and to improve their tunability, processability, power conversion efficiency, and stability. On the eve of commercialization of organic solar cells, this review provides an overview over efficiencies attained with small molecules/oligomers in OSCs and reflects materials and device concepts developed over the last decade. Approaches to enhancing the efficiency of organic solar cells are analyzed.