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A study was conducted to analyze the effect of large leakage currents in defining the device active region in photodetectors. The design of planar photodeterctors should be based on the findings of hole leakage currents that shift the active region inside the channel and drastically slow the device time response.

Planar organic detectors for the near infrared region of the light spectrum have been realized, processing from solution the quinoid molecule 5,5′-bis(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadiene-1-ylidene)-5,5′-dihydro-2,2′-bithiophene (QBT), which shows a peculiar absorption at 680 nm. Sensitization of the active material was obtained by creating a bulk donor-acceptor interface with poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene], which acts as hole acceptor. Photoexcitation and relaxation dynamics in pristine materials and bulk heterojunction have been investigated by means of pump-probe measurements, revealing charge transfer from QBT to polymer and efficient energy transfer the other way round. [ABSTRACT FROM AUTHOR]

The paper studies the role of electrons and holes mobility in determining the external quantum efficiency (EQE) in photodetectors based on a 1:1 in weight blend of poly(3-hexylthiophene) (P3HT) and C61-butyric acid methyl ester (PCBM). In order to fairly correlate the optoelectronic properties (efficiency and transient photocurrent) measured on photodetectors with the transport properties measured on field effect transistors, the photodetectors and the transistors have been produced with an identical planar geometry, where in both cases the charges flow occurs in the same direction with respect to the substrate. The measurements have been performed on devices based on pristine P3HT, on pristine PCBM, and on P3HT:PCBM 1:1 blend, before and after annealing, and have revealed the importance of a balanced carrier transport, showing that quantum efficiency increases as long as the mobility of electrons, which are the slowest carrier, increases. On the other end, the response time is mainly affected by the extension of the effective area. [ABSTRACT FROM AUTHOR]

The possibility of realizing fast and efficient near-infrared (NIR) light detectors is explored based on bulk heterojunction of a p-diphenoquinone analog extended by di-hydrobithiophenediylidene, a quinoid molecule featuring a high absorption band and poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene]. Photoexcitation and relaxation dynamics in pristine materials and bulk heterojunction are examined by using pump-probe measurements, disclosing charge transfer from 5,5'-bis(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadiene-1-ylidene)-5,5'-dihydro-2,2'-bithiophene (QBT) to polymer and efficient energy transfer the other way round.

Organic diodes manufactured on a plastic substrate capable of rectifying a high-frequency radio-frequency identification signal (13.56 MHz), with sufficient power to operate an interactive smart tag, are reported. A high-performance conjugated semiconductor (an indacenodithiophene-benzothiadiazole copolymer) is combined with a carefully optimized architecture to satisfy the electrical requirements for an organic-semiconductor-based logic chip., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We investigate the reasons for the dependence of photovoltaic performance on the absorber thickness of organic solar cells using experiments and drift-diffusion simulations. The main trend in photocurrent and fill factor versus thickness is determined by mobility and lifetime of the charge carriers. In addition, space charge becomes more and more important the thicker the device is because it creates field free regions with low collection efficiency. The two main sources of space-charge effects are doping and asymmetric mobilities. We show that for our experimental results on Si-PCPDTBT:PC71BM (poly[(4,40-bis(2-ethylhexyl)dithieno[3,2-b:20,30-d]silole)-2,6-diyl-alt-(4,7-bis(2-thienyl)-2,1,3-benzothiadiazole)-5,50-diyl]:[6,6]-phenyl C71-butyric acid methyl ester) solar cells, the influence of doping is most likely the dominant influence on the space charge and has an important effect on the thickness dependence of performance.

Grazing incidence X-ray diffraction (GI-XRD) is used to characterize the crystallographic dynamics of low molecular weight (LMW) and high molecular weight (HMW) poly(3-hexylselenophene) (P3HS) films and blend films of P3HS with [6-6-]-phenyl-C(61) -butyric acid methyl ester (PCBM) as a function of 'step-by-step' thermal annealing, from room temperature to 250 °C. The temperature-dependent GIXRD data show how the melting point of P3HS crystallites is decreased by the presence of PCBM. P3HS crystallite domain sizes dramatically increase upon annealing to the P3HS melting temperature. The formation of well-oriented HMW P3HS crystallites with the (100) plane parallel to the substrate (edge-on orientation), when cooled from melt, are observed. We compare the behaviour of P3HS pure and blend films with that of poly(3-hexyl)thiophene (P3HT) pure and PCBM blended films and suggest that the similar temperature dependent behaviour we observe may be a common to polythiophene and related polymers and their blends., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Control of blend morphology at the microscopic scale is critical for optimizing the power conversion efficiency of plastic solar cells based on blends of conjugated polymer with fullerene derivatives. In the case of bulk heterojunctions of regioregular poly(3-hexylthiophene) (P3HT) and a soluble fullerene derivative ([6,6]-phenyl C61-butyric acid methyl ester, PCBM), both blend morphology and photovoltaic device performance are influenced by various treatments, including choice of solvent, rate of drying, thermal annealing and vapour annealing. Although the protocols differ significantly, the maximum power conversion efficiency values reported for the various techniques are comparable (4-5%). In this paper, we demonstrate that these techniques all lead to a common arrangement of the components, which consists of a vertically and laterally phase-separated blend of crystalline P3HT and PCBM. We propose a morphology evolution that consists of an initial crystallization of P3HT chains, followed by diffusion of PCBM molecules to nucleation sites, at which aggregates of PCBM then grow.

The purpose of this study is to determine the effect of terminal sterilization by gamma irradiation on 500-mL amber Type I and Type III glass containers (bottles) containing oxytetracycline (OTC) (25% W/V) suspension formulated using 20% (W/V) phospholipids syrup. The formulation was developed for veterinary parenteral administration. The results of terminal sterilization were used to assess the acceptability for this suspension product. OTC is light-sensitive and needs to be stored in amber glass containers. Amber Type I and Type III glass containers were considered for this formulation during development. Type I is a highly resistant, borosilicate glass (oxidized glass). Type III, which is soda-lime glass (reduced glass, see Materials and Methods), may also be used for parenteral products. The amber Type I and Type III glass containers, containing the suspension, were irradiated at 20-40 kGy for 150 min. In order to determine the sterility of the suspension, ampoules of the biological indicator, Bacillus pumilus, were placed in a number of bottles of the suspension. The bottles with the biological indicators were then positioned among the rest of the production bottles as per a radiation dose-mapping study conducted at the sterilization facility. Potency determination and stability evaluations for OTC were performed using high pressure liquid chromatography (HPLC). The results indicate that the gamma irradiation dose of 20-40 kGy for 150 min was able to inactivate 10(6) Bacillus pumilus spores in ampoules. After gamma sterilization, OTC concentration, pH, particle size, endotoxins, and sterility were evaluated. The assay results were comparable for the suspension in amber Type I and Type III glass containers. Sterility and pyrogenicity were measured by the USP Membrane Filtration Method and USP Bacterial Endotoxins Test, respectively. The suspension in the amber Type III glass container was also chemically (HPLC) and physically (suspension mean particle size, viscosity, density, and syringeability) stable for at least 12 months at room temperature. However, amber Type I glass darkened following irradiation, leading to a substantial reduction in glass transparency. The appearance of amber Type III glass was acceptable. Thus, the "reduced" glass, such as soda-lime, was found to be much less susceptible to darkening than the highly oxidized borosilicate amber. Due to the potential aesthetic concerns with Type I glass, the amber Type III glass container was selected for this suspension formulation.