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This paper is concerned with the photophysics of triplet excitons in conjugated donor polymers, and their quenching by molecular oxygen. These photophysics are assayed by transient absorption spectroscopy, and correlated with X-ray diffraction measurements of relative material crystallinity. Eleven different donor polymers are considered, including representatives from several classes of donor polymers recently developed for organic solar cell applications. Triplet lifetimes in an inert (nitrogen) environment range from <100 ns to 5 μs. A remarkably quantitative correlation is observed between these triplet lifetimes and polymer XRD strength, with more crystalline polymers exhibiting shorter triplet lifetimes. Given the broad range of polymers considered, this correlation indicates that material crystallinity is the dominant factor determining triplet lifetime for the polymers studied herein. The rate constant for oxygen quenching of these triplet states, determined from a comparison of transient absorption data under inert and oxygen environments, also show a correlation with material crystallinity. Overall these dependencies result in the yield of oxygen quenching of polymer triplet states increasing strongly as the crystallinity of the polymer is reduced. These photophysical data are compared with photochemical stability of these donor polymers, assayed by photobleaching studies of polymer films under continuous light exposure in an oxygen environment. A partial correlation is observed, with the most stable polymers being the most crystalline, exhibiting negligible oxygen quenching yields. These results are discussed in terms of the likely origins of the correlations between material crystallinity and photophysics, and in terms of their implications for the environmental stability of such donor polymers in optoelectronic devices. [ABSTRACT FROM AUTHOR]

A series of donor-acceptor (D-A) conjugated polymers utilizing 4,4-bis(2-ethylhexyl)-4 H-germolo[3,2- b:4,5- b′]dithiophene ( DTG) as the electron rich unit and three electron withdrawing units of varying strength, namely 2-octyl-2 H-benzo[ d][1,2,3]triazole ( BTz), 5,6-difluorobenzo[ c][1,2,5]thiadiazole ( DFBT) and [1,2,5]thiadiazolo[3,4- c]pyridine ( PT) are reported. It is demonstrated how the choice of the acceptor unit ( BTz, DFBT, PT) influences the relative positions of the energy levels, the intramolecular transition energy (ICT), the optical band gap ( Egopt), and the structural conformation of the DTG-based co-polymers. Moreover, the photovoltaic performance of poly[(4,4-bis(2-ethylhexyl)-4 H-germolo[3,2- b:4,5- b′]dithiophen-2-yl)-([1,2,5]thiadiazolo[3,4- c]pyridine)] ( PDTG-PT), poly[(4,4-bis(2-ethylhexyl)-4 H-germolo[3,2- b:4,5- b′]dithiophen-2-yl)-(2-octyl-2 H-benzo[ d][1,2,3]triazole)] ( PDTG-BTz), and poly[(4,4-bis(2-ethylhexyl)-4 H-germolo[3,2- b:4,5- b′]dithiophen-2-yl)-(5,6-difluorobenzo[ c][1,2,5]thiadiazole)] ( PDTG-DFBT) is studied in blends with [6,6]-phenyl-C70-butyric acid methyl ester ( PC70BM). The highest power conversion efficiency (PCE) is obtained by PDTG-PT (5.2%) in normal architecture. The PCE of PDTG-PT is further improved to 6.6% when the device architecture is modified from normal to inverted. Therefore, PDTG-PT is an ideal candidate for application in tandem solar cells configuration due to its high efficiency at very low band gaps ( Egopt = 1.32 eV). Finally, the 6.6% PCE is the highest reported for all the co-polymers containing bridged bithiophenes with 5-member fused rings in the central core and possessing an Egopt below 1.4 eV. [ABSTRACT FROM AUTHOR]

The synthesis and characterizationof four new donor–acceptortype semiconducting polymers based on the electron-deficient diketopyrrolopyrroleunit for use in photovoltaic devices are reported. The extended 2-decyl-1-tetradecylalkyl chain (C10C12) is utilized to providea valuable route toward enhanced solubility. The resultant solubleDPP polymers were synthesized in high polymer molecular weights witha larger range of accessible comonomer units. Bulk heterojunctionsolar cells containing these polymers show promising device performancewith efficiencies around 4%. Organic thin film transistor deviceswith high ambipolarhole mobilities of >0.1 cm2V–1s–1are also reported. [ABSTRACT FROM AUTHOR]

The organosulfur compounds present in liquid fuels are hazardous for health, asset, and the environment. The photocatalytic desulfurization technique works at ordinary conditions and removes the requirement of hydrogen, as it is an expensive gas, highly explosive, with a broader flammability range and is declared the most hazardous gas within a petroleum refinery, with respect to flammability. The projected work is based on the synthesis of V2O5 microspheres for photocatalytic oxidation for the straight-run diesel (SRD) and diesel oil blend (DOB). The physicochemical properties of V2O5 microspheres were examined by FT-IR, Raman, UV-vis DRS, SEM, and Photoluminescence evaluations. The as-synthesized photocatalyst presented a trivial unit size, a narrow bandgap, appropriate light-capturing capability, and sufficient active sites. The desulfurization study discovered that the anticipated technique is substantial in desulfurizing DOB up to 37% in 180 min using methanol as an interfacing agent. Furthermore, the outcome of employing a range of polar interfacing solvents was examined, and the 2-ethoxyethanol elevated the desulfurization degree up to 51.3%. However, the anticipated technology is constrained for its application in sulfur removal from SRD. Additionally, the mechanism for a photocatalytic reaction was seen in strong agreement with pseudo-first-order kinetics. The investigated photocatalyst exhibited a compromised recyclability and regeneration tendency. [ABSTRACT FROM AUTHOR]

This review article provides a comprehensive overview of recent advancements in electron transport materials derived from quinoxaline, along with their applications in various electronic devices. We focus on their utilization in organic solar cells (OSCs), dye-sensitized solar cells (DSSCs), organic field-effect transistors (OFETs), organic-light emitting diodes (OLEDs) and other organic electronic technologies. Notably, the potential of quinoxaline derivatives as non-fullerene acceptors in OSCs, auxiliary acceptors and bridging materials in DSSCs, and n-type semiconductors in transistor devices is discussed in detail. Additionally, their significance as thermally activated delayed fluorescence emitters and chromophores for OLEDs, sensors and electrochromic devices is explored. The review emphasizes the remarkable characteristics and versatility of quinoxaline derivatives in electron transport applications. Furthermore, ongoing research efforts aimed at enhancing their performance and addressing key challenges in various applications are presented., (Copyright © 2023, Abid et al.)

Cost-effective, solution-processable organic photovoltaics (OPV) present an interesting alternative to inorganic silicon-based solar cells. However, one of the major remaining challenges of OPV devices is their lack of long-term operational stability, especially at elevated temperatures. The synthesis of a fullerene dumbbell and its use as an additive in the active layer of a PCDTBT:PCBM-based OPV device is reported. The addition of only 20 % of this novel fullerene not only leads to improved device efficiencies, but more importantly also to a dramatic increase in morphological stability under simulated operating conditions. Dynamic secondary ion mass spectrometry (DSIMS) and TEM are used, amongst other techniques, to elucidate the origins of the improved morphological stability., (© 2014 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.)

We report the synthesis and polymerization of a novel thieno[3,2-b]thiophene-diketopyrrolopyrrole-based monomer. Copolymerization with thiophene afforded a polymer with a maximum hole mobility of 1.95 cm(2) V(-1) s(-1), which is the highest mobility from a polymer-based OFET reported to date. Bulk-heterojunction solar cells comprising this polymer and PC(71)BM gave a power conversion efficiency of 5.4%.