Fresh Films Research Articles

Trypanosoma vivax in and outside cattle blood: Parasitological, molecular, and serological detection, reservoir tissues, histopathological lesions, and vertical transmission evaluation

This study reports assessment of the sensitivity of diagnostic techniques to detect T. vivax in experimentally infected cattle. Additionally, it describes T. vivax extravascular parasitism during the acute and chronic phases of trypanosomosis and congenital transmission. The T. vivax diagnosis was compared using blood samples collected from the jugular, coccygeal and ear tip veins. For this study, 13 males and two females were infected with ≈ 1 × 106 viable T. vivax trypomastigotes (D0). One animal was kept as a negative control during the entire study. The 13 infected males were euthanized between 14 and 749 days post-infection (DPI). After confirming the cyclicity of both females (9 months of age), they were naturally mated with a bull. One female was euthanized at 840 DPI, and the other at 924 DPI. The two calves, one from each female, were euthanized at six months of age (924 DPI), and the negative control at 924 DPI. During this period, T. vivax in blood was assessed using direct methods (Woo test, cPCR, microscopic examination of fresh wet blood films and parasite quantification - Brener method), and serological methods (IFAT, ELISA, and IA). Tissue samples were collected from the liver, spleen, brain, cerebellum, heart, testicles, epididymis, kidneys, eyeballs, pre-scapular lymph nodes, ear tips, mammary glands, uterus, and ovaries. The protozoan DNA was examined using LAMP. There was no difference in the detection of T. vivax using the Woo test and Brener method among the jugular, coccygeal, and ear tip veins. The sensitivity of the detection methods varied depending on the disease phase. Direct methods (Woo test, Brener method, and cPCR) demonstrated higher sensitivity during the acute phase, while serological methods (IFAT, ELISA, and IA) were more sensitive during the chronic phase. Anti-T. vivax antibodies were detected up to 924 DPI. Tissue evaluation using LAMP demonstrated the presence of T. vivax DNA and associated histopathological changes up to 840 or 924 DPI. Only in mammary glands and ovaries was no DNA detected. The most frequently observed histopathological alteration was lymphohistioplasmocytic inflammatory infiltrate. No transplacental transmission of T. vivax was observed.

Fault-tolerant structures against breakdown in heterogeneous ferroelectric PbZr0.52Ti0.48O3 thin films based on adaptive self-repairing effects

The design of fault-tolerant structures against the breakdown of heterogeneous ferroelectric films is essential to enhance the breakdown strength. Based on the self-repairing theory, heterogeneous ferroelectric PbZr0.52Ti0.48O3 (PZT) film capacitors with a fault-tolerant structures against breakdown were synthesized by utilizing dielectric/electrolytic dual characteristics of the amorphous aluminum oxide film (AmAO). The PZT/AmAO composite films with Au top electrodes exhibited significant weak breakdown at low voltages, whereas the breakdown in the composite films with Al top electrodes have been repaired and no longer occurred. Compared to PZT(100 nm)/AmAO(120 nm) composite films with Au top electrodes, breakdown strength of PZT(100 nm)/AmAO(120 nm) composite films with Al top electrodes improves from 278 MV/m to 477 MV/m, energy storage density increased from 14.3 J/cm3 to 22.5 J/cm3, since the heterogeneous interface and structural defects have been repaired by adaptive anodizing of Al electrode under high electric field. Cross-sectional SEM images have confirmed the formation of fresh aluminium oxide films (AAO) at the interfaces of AmAO/Al and PZT/AmAO during the application of an electric field. Defects have been effectively repaired, resulting in an increase in breakdown strength. This study establishes a theoretical and technical foundation for the design of fault-tolerant structures against breakdown in heterogeneous ferroelectric films.

Efficient Fresh Lamp Light-Harvesting Films with the Self-Activating Continuous and Recyclable Bactericidal Ability for Ultrapersistent Freshness of Perishable Muscle Food.

A large quantity of perishable muscle food is being wasted due to harmful bacteria infestation during the sales and circulation each year and facing challenges. In this study, a self-activated bactericidal active film (PLA/g-C3N4@PCN-224) responsive to fresh lamp light was prepared, which showed excellent hydrophobicity, water vapor resistance, and thermal stability. Due to the synergistic effect between light-induced reactive oxygen species and the high specific surface area of g-C3N4@PCN-224, this film still maintains 99.99% bactericidal efficacy against Escherichia coli and Staphylococcus aureus after 10 days of continuous bactericidal activity test. The results of cell and hemolysis experiments indicated that the film was safe and nontoxic and can effectively preserve fresh pork for 7 days. Moreover, the film also exhibited a recyclable and efficient killing activity. A strategy for achieving ultrapersistent freshness of perishable muscle food was provided.

The Structural Changes and Its Impact on Optical Dispersion of PVA/PVP Embedded with Zinc Sulphate Nanoparticles and Irradiated with Electron-Beam

PVA/PVP films doped with zinc sulphate heptahydrate (ZnSO4·7H2O) nanoparticles (NPs) are prepared using an in situ chemical method. Furthermore, as-prepared samples are irradiated with an electron beam at doses of 20, 25, 30, 35, and 40 kGy. Elemental analyses using energy dispersive X-ray spectroscopy (EDXS) of the fresh films showed the existence of both zinc oxide and zinc sulphide as main and minor phases in sequence. Moreover, scanning electron microscope measurements (SEM) revealed that embedded Zn NPs have regular and evenly distributed pores inside PVA/PVP network. On the other hand, the structural variations due to e-beam irradiation are monitored by a high-resolution-transmission electron microscope (HR-TEM), which displayed that encapsulated Zn NPs are well dispersed and capped inside PVA/PVP structural network. The measured optical absorption coefficient (α) of PVA/PVP/zinc sulphate nanocomposite films showed an increase against e-beam dose. Moreover, the calculated optical energy gap, Eg, exhibited a reduction from 3.31 to 2.82 eV against the increase in irradiation dose. Evaluated values of wavelength at zero material dispersion (WZMD) indicated that e-beam irradiation can tune the structure of the studied samples to be used as a data transmitter in optical fiber telecommunication in the IR spectral range of 1.6842–1.0351 μm.

Mastering morphology of non-fullerene acceptors towards long-term stable organic solar cells

Despite the rapid progress of organic solar cells based on non-fullerene acceptors, simultaneously achieving high power conversion efficiency and long-term stability for commercialization requires sustainable research effort. Here, we demonstrate stable devices by integrating a wide bandgap electron-donating polymer (namely PTzBI-dF) and two acceptors (namely L8BO and Y6) that feature similar structures yet different thermal and morphological properties. The organic solar cell based on PTzBI-dF:L8BO:Y6 could achieve a promising efficiency of 18.26% in the conventional device structure. In the inverted structure, excellent long-term thermal stability over 1400 h under 85 °C continuous heating is obtained. The improved performance can be ascribed to suppressed charge recombination along with appropriate charge transport. We find that the morphological features in terms of crystalline coherence length of fresh and aged films can be gradually regulated by the weight ratio of L8BO:Y6. Additionally, the occurrence of melting point decrease and reduced enthalpy in PTzBI-dF:L8BO:Y6 films could prohibit the amorphous phase to cluster, and consequently overcome the energetic traps accumulation aroused by thermal stress, which is a critical issue in high efficiency non-fullerene acceptors-based devices. This work provides insight into understanding non-fullerene acceptors-based organic solar cells for improved efficiency and stability.

Two colorimetric films based on chitin whiskers and sodium alginate/gelatin incorporated with anthocyanins for monitoring food freshness

Intelligent food packaging materials from natural resources has attracted increasing attention nowadays. In this paper, two fresh colorimetric films were obtained by incorporating natural pigment anthocyanins extract (LRM) as pH-sensitive pigments into two polyelectrolyte complex films composed of chitin whiskers (CW) and sodium alginate (SA)/gelatin (GE), respectively. The analysis results of FTIR, SEM and DSC show that, compared with the single polysaccharide system of SA or GE, the composite film with addition of CW has better water resistance and thermal stability, due to the existence of hydrogen bonds and electrostatic interactions. Meanwhile, the adhesion to LRM is also enhanced. At the same time, through Ritger–Peppas kinetic model analysis, the release process of anthocyanins in the two film systems was analyzed. The CW/SA/LRM system membrane showed good responsiveness to lactic acid and was successfully used in the detection of milk freshness; while the CW/GE/LRM system membrane showed good responsiveness to amine gases and has been successfully used in the detection of pork freshness. The study revealed that the above colorimetric films demonstrate excellent durability and accuracy in food freshness monitoring.

High mechanical performance Cu-intercalated layered h-BN/N-doped carbon-nanofiber composite films for selective adsorption desulphurization

The Cu-intercalated layered h-BN/N-doped carbon-nanofiber composite films (PAN-Cu/ABN-CNFs) were successfully prepared by the combination of the electrospinning technique and the one-pot carbonization process, using the mixed solution of polyacrylonitrile (PAN) and Cu-intercalated activated boron nitride (Cu/ABN) as carbon precursor. A series of characterizations proved that the PAN-Cu/ABN-CNFs possessed the distinguished merits in the structure and composition, such as the pore feature of the micropore (0.076 cm3/g)-mesoporous (0.3582 cm3/g) structure, the structure of the exfoliated h-BN nanosheets, the low-coordination high-content N (11.65 at%) and the existence of self-reducing Cu nanoparticles (0.5 at%). For adapting the actual application, the mechanical properties of the PAN-Cu/ABN-CNFs were comprehensively evaluated, showing that the PAN-Cu/ABN-CNFs films had the robust tensile strength and bending properties as well as the desirable wear resistance. Furthermore, the selective adsorption desulphurization of the PAN-Cu/ABN-CNFs were examined by the selective adsorption removal of thiophene (TH) from the simulated oil, indicating that the optimum adsorption capacity of the fresh films was up to 78.38 mg/g in 800 mg/L initial concentration and the adsorption capacity after the four-time regeneration recycling still approached 74.894 mg/g. Finally, the adsorption kinetics, isotherm and thermodynamic studies suggested that the adsorption behavior of TH over the PAN-Cu/ABN-CNFs should be better described by the correlation coefficients of Avrami fractional-order kinetics and Liu isotherm, while the thermodynamic studies showed a favorable exothermic and spontaneous adsorption mechanism.

EFFECT OF LOW-ENERGY OXYGEN ION BEAM TREATMENT ON THE STRUCTURAL AND PHYSICAL PROPERTIES OF ZnO THIN FILMS

In this paper, we report the influence of low-energy oxygen ion irradiation with fluence ranging from [Formula: see text][Formula: see text][Formula: see text] to [Formula: see text][Formula: see text][Formula: see text] on the structural, optical, and electrical properties of fresh and annealed (400∘C, 3[Formula: see text]h) zinc oxide (ZnO) thin films. These films were grown on soda-lime glass (SLG) substrates using the spin-coating method as a low-cost depositing technique. X-ray diffraction (XRD) study showed the formation of the hexagonal phase of ZnO thin films with preferred orientation along the (002) plane. The crystallite size for fresh and annealed ZnO thin films was in nanoscale and it increased with the annealing temperature. Also, the crystallite size increased with the ion beam irradiation fluence in the case of annealed ZnO films, while it slightly decreased for the fresh ZnO films. The transmittance and absorbance spectra for the ZnO films were investigated in a wide wavelength range. The optical bandgap was specified by using Tauc’s relation. The electrical properties of the ZnO films (fresh and annealed at 400∘C for 3[Formula: see text]h) were studied before and after the oxygen ion beam irradiation. Also, the dielectric properties were investigated with respect to frequency at different ion beam irradiation fluences. The comprehensive results showed the dielectric and optical properties are improved due to the induced conductive networks by oxygen ion irradiation.

Effects of Annealing Time on Triple Cation Perovskite Films and Their Solar Cells.

Cesium (Cs) contained triple-cation and mixed halide perovskite (CsFAMA) is broadly employed as light absorption layers for efficient and stable perovskite solar cells (PSCs) fabrication with high reproducibility. On the other hand, thermal annealing is a universal post-treatment method for perovskite films preparation. Moreover, thermal management highly depends on perovskite materials. However, no specialized study has been reported on CsFAMA perovskite to date. Herein, we have systematically investigated the influence of thermal annealing and annealing time on CsFAMA films and their solar cells. We demonstrated that heating time of 45 or 60 min at 100 °C is desirable. More interestingly, we found that the unannealed CsFAMA films exhibit ultrahigh photoluminescence (PL) intensities, much stronger than that of annealed films. Note that PL intensities gradually weaken as a function of annealing time. In particular, the PL intensities of fresh films (after antisolvent dripping) are at least 200 times higher than that of 60 min annealed films. To our knowledge, it is the first time to report this PL behavior. We speculate that it is due to quantum confinement effect of perovskite crystal nuclei and "cage effect" of DMSO intermediates in the fresh films. To this point, the unannealed CsFAMA films may have great potential in PL emission applications.

Comparative study of thermochromic properties on fresh and aged vanadium dioxide films

Vanadium dioxide (VO2) thin films were fabricated by means of DC reactive magnetron sputtering at low temperature, and then were aged in air for 5 years. The thermochromic properties of the fresh VO2 film and aged one were investigated by UV–visible spectrophotometer. The experimental results show that the fresh VO2 film shows excellent thermochromic properties with a high visible transmittance of 40.8% and a large switching efficiency of 73% at 2500 nm. For the film aged in ambient air for 5 years, the visible transmittance is increased to 54.0% due to a blue-shift of absorption edge and a decrease in luminous absorbance. More interestingly, the aged VO2 film still keeps a relatively large switching efficiency of 51% at 2500 nm, suggesting the deposited VO2 film has a good thermochromic stability in ambient air. These characteristics indicate the practical applications of VO2 film to smart optical devices.

Films of Chitosan and Aloe vera for Maintaining the Viability and Antifungal Activity of Lactobacillus paracasei TEP6

The present study aimed to evaluate the effect of Aloe vera addition on the viability and antifungal activity of TEP6 (Lactobacillus paracasei) bacteria immobilized on chitosan films for 28 days. Different chitosan and A. vera proportions and carbon sources at several pH values were tested as formulations for supporting the microorganism. Bacterial viability was maintained in freshly made films, with values of 10.4, 10.8 and 10.9 log CFU·g−1 for the formulations containing 70% (T11), 100% (T8) and 100% (T16) of A. vera, respectively. The same formulations (T8, T11 and T16) maintained bacterial viability for 14 days of film storage with a loss to values of 9.5 log CFU·g−1. By applying a quarter fraction 25–2 experimental design with an array of five factors, the factors with the greatest influence on viability and antifungal activity were determined. The optimal conditions for viability were the formulation with 100% A. vera, pH 4.5 and 0.1 M glucose. The antifungal activity of fresh films was influenced by the formulation with 10 g·L−1 glycerol and 100% A. vera, showing a 60% inhibition of fungal (Colletotrichum gloeosporioides) growth. The films developed in this study may have the potential to be used as coatings on vegetal products susceptible to attack by Colletotrichum gloesporioides.

High crystallinity and photovoltaic performance of CsPbI3 film enabled by secondary dimension

Abstract The photovoltaic performance of perovskite sloar cells (PSCs) is strongly dependent on the crystallinity, morphorlogy and defects of perovskite films. In the present work, a novel strategy was developed to fabricate the high quality CsPbI3 inorganic perovskite by tuning the growth dynamics of CsPbI3 by pretreatment of fresh CsPbI3 films with phenylethylamine iodide (PEAI). The PEAI can mediate the phase transformation from 1D (DMAPbI3) (DMA: dimethylammonium) to 3D CsPbI3 all-inorganic perovskite films via the PEA2CsPb2I7 of 2D perovskite intermediate phase, resulting in highly crystalline CsPbI3 perovskite films with remarkably enlarged grains and reduced defects. The as-achieved highly crystalline CsPbI3 inorganic perovskite not only exhibited improved phase stability but also significant reduced defects. The perovskite solar cells based on these CsPbI3 thin films exhibited a champion efficiency of 17.08%, much higher than those prepared through posttreatment or direct addition of PEAI into CsPbI3 precursor solution. This work not only developed an effective strategy to prepare high crystalline CsPbI3 film and highly efficient CsPbI3-based all-inorganic PSCs, but also unraveled the mediation mechanism of CsPbI3 by pre-treatment of PEAI, shedding light for further development of high perfomance perovskite-based optoelectronics.

Synthesis and Characterization of γ-Irradiated Cadmium Sulfide/Polyvinyl Alcohol Nanocomposites Films

CdS (Cadmium Sulfide)/PVA (Polyvinyl Alcohol) nanocomposite films were prepared using a solution casting method. Transmission electron microscopy (TEM) showed that CdS nanoparticles (NPs) have particle size < 20 nm. X-ray diffraction (XRD) were used to check the crystal structure, grain size of CdS NPs in Polyvinyl alcohol (PVA) and the change in grain size of CdS with γ-irradiation doses. Fourier transform infrared (FTIR) spectroscopy has confirmed the dispersion of CdS NPs in PVA for fresh and γ-irradiated films, where a substantial change in band position (OH stretching) was noted due to the interaction between CdS NPs and the host PVA polymer matrix. Conductivities (DC/AC) and dielectric properties were used to characterize the final nanocomposite films before and after γ-irradiation with distinct doses. Upon increasing the amount of CdS NPs an increase in the dielectric constant (e1), dielectric loss (e2) and AC conductivity of PVA films host was observed. In addition, the DC and AC conduction of the PVA films as a polymeric host material was improved with the CdS NPs content and γ-irradiation doses.

Electrochemically and chemically deposited polycrystalline CdSe electrodes with high photoelectrochemical performance by recycling from waste films

Waste CdSe film electrodes can be recycled into useful films without sacrificing their photoelectrochemical performance. Cd2+ aqueous ions have been recovered from waste CdSe electrodes by soaking in minimal amount of HCl (10.0 M) at 80 °C for 60 min. The Se2− ions, converted into H2Se(g) by the acid, have been trapped in basic NaOH solution for further use. The recovered Cd2+ ions have been used to deposit new (recycled) CdSe film electrodes onto fluorine doped tin oxide films (FTO/Glass) using aqueous Na2SeSO3 solutions by two methods. Electrochemical deposition (ECD) has been performed using applied potential (−1.0 V vs Ag/AgCl). Chemical bath deposition (CBD) has been performed in a basic medium at 70 °C. Both ECD and CBD recycled films have been prepared using recovered Cd2+ solutions, whereas fresh films have been prepared using fresh solutions. In both cases, the recycled CdSe films do not show any inferior characteristics to the freshly prepared counterparts. Effects of annealing at 150 °C and cooling rate on physical and photoelectrochemical (PEC) characteristics have been studied for different CdSe film electrodes. In both recycled and fresh systems, the CBD film electrodes exhibit enhanced uniformity, compactness and photo-electrochemical (PEC) performance by annealing. Upon annealing, the recycled and fresh ECD films exhibit less film uniformity and compactness, and consequently lower PEC performance. In ECD and CBD films, fast cooling is advantageous over slow cooling. Conversion efficiency values of ~8% are observed for the CBD recycled pristine films once carefully annealed and quickly cooled. This is higher than literature values for pristine CdSe (~5%), TiO2/CdS/CdSe (~4%) film electrodes, and resembles that for Tl/CdSe0.65Te0.35 (~8) multi-layer systems. The results show the feasibility of recycling waste CdSe film electrodes.

Efficient Anti-solvent-free Spin-Coated and Printed Sn-Perovskite Solar Cells with Crystal-Based Precursor Solutions

Summary Tin-based perovskite solar cells (PSCs), with more consummate optical band gaps, lower exciton-binding energies, and higher charge-carrier mobility, have not attracted tremendous research efforts compared with the lead-based ones that have a record power conversion efficiency (PCE) of 24.2%. The major challenges for Sn-based research are significantly low open-circuit voltage, poor reproducibility, and environmental instability. It has been identified that the oxidation processes take place during the preparation of precursor solutions and fabrication of films, due to the low redox potential of the stannous absorption layer. Herein, we propose two strategies of crystal-resolving and recrystallization technology to reduce the oxidation process. As a result, PCEs of 8.9% (active area of 0.04 cm2) and 5.5% (active area = 1.01 cm2) are attained using the inverted p-i-n structure, which will lead to a revival of lead-free PSC research.

Preparation and partial characterization of films made with dual-modified (acetylation and crosslinking) potato starch.

Starch is an alternative material for the production of biodegradable plastics; however, native starches have drawbacks due to their hydrophilic nature. Chemical modifications such as acetylation and crosslinking are used to broaden the potential end-uses of starch. Dual modification of starches increases their functionality compared to that of starches with similar single modifications. In this study, a dual-modified potato starch (acetylated and crosslinked) was used to produce films by casting. Changes in the arrangement of the amylopectin double helices of dual-modified starch were evident from X-ray diffraction patterns, pasting profiles and thermal properties. The degree of substitution for acetyl groups was low (0.058±0.006) because crosslinking dominated acetylation. Modified starch film had higher elongation percentage (82.81%) than its native counterpart (57.4%), but lower tensile strength (3.51MPa for native and 2.17MPa for dual-modified) and lower crystallinity in fresh and stored films. The sorption isotherms indicated that the dual modification decreased the number of reactive sites for binding water, resulting in a reduction in the monolayer value and a decrease in the solubility and water vapor permeability. Dual modification of starch may be a feasible option for improving the properties of biodegradable starch films. © 2018 Society of Chemical Industry.

Optical activity anisotropy of chitosan-based films

The optical activity [α] of films of chitosan and chitosan acetate was studied. [α] depended on the orientation angle θ of the film sample around the light beam. The angular dependences [α] = f(θ) (indicatrices) were processed to extract the constant term [α]0and four harmonics ([α]i, Fourier’s series) determined by structure elements with the corresponding symmetry: the amorphous (isotropic) phase of chitosan ([α]0), irregular-shaped structures ([α]1), rod-shaped ones in the film plane ([α]2), helical ones located perpendicular to the film surface ([α]3), and crystalline structures ([α]4). The contribution of individual supramolecular structures to the overall optical activity of chitosan was estimated: [α]2 and [α]4 predominated for the fresh chitosan acetate films, while [α]4 did for the chitosan ones. The results of the numerical decomposition of indicatrices are in satisfactory agreement with X-ray diffractometry data. The observed regularities predetermine prospects for obtaining stereoselective chiro-optic chitosan-based materials with novel functional properties.

Retention and release properties of cinnamon essential oil in antimicrobial films based on chitosan and gum arabic

Film-forming dispersions and films based on chitosan (CS), gum arabic (GA) and cinnamon essential oil (CEO) were prepared. The influence of different mass ratios of CS/GA on properties of film-forming dispersions and antimicrobial activities of films were characterized. Especially, the effects of CS/GA ratios on the retention and release properties of CEO were quantified. Results showed that a lower ζ-potential and smaller particle size were obtained with increasing GA ratios from 1:0 to 1:2, indicating electrostatic interactions occurred between CS and GA. Fluorescence microscopy results demonstrated higher retention and less aggregation of CEO in the composite films, meaning increased compatibility of the multiphased system when proportions of GA increased from 1:0 to 1:2. The loss of CEO in fresh films (day 0) was reduced from 54.56% to 34.23% and its retention time during storage was increased up to 15 days. TGA analysis further verified higher retention of CEO during heating. In addition, a delayed and sustained release of CEO was observed, thus enhancing antimicrobial activities of composite films. However, when the ratio of CS/GA was at 1: 4, the electrostatic interactions between CS and GA tended to reach maximum, leading to the formation of insoluble complexes, which was not beneficial for the retention and release properties of CEO in composite films.

Stability and reactivity of γ-ΜPTMS silane in some commercial primer and adhesive formulations

ObjectivesTo evaluate the stability and reactivity of γ-methacryloxypropyl trimethoxysilane (MPTMS) in commercially available primers and adhesives. MethodsFour representative primer formulations [Calibra Silane Coupling Agent/Dentsply (CLB), G-Multi Primer/GC (GMP), Kerr Silane Primer/Kerr (KSP), Monobond Plus/Ivoclar Vivadent (MBP)] and a universal adhesive [Scotchbond Universal/3M ESPE (SBU)] containing MPTMS were analyzed spectroscopically. For the stability study, the silanol content was evaluated in bulk solutions as received (reference-RE) and after aging (AG, 48°C/1month) by 1H, 13C, 31P NMR and in fresh films by transmission FTIR analysis (TIR, films applied on Ge windows after solvent evaporation). The reactivity, as expressed by the siloxane formation capacity of the RE products, was evaluated by micro-multiple internal reflectance FTIR analysis (MIR, films applied on Ge crystals) after drying and ethanol rinsing (t0) and following 1 (t1) and 24h (t24) storage (air/37°C). ResultsNMR and TIR showed ∼60% MPTMS silanol groups in RE-CLB, with the other (∼40%) groups being methylated or ethoxylated. In AG-CLB, the silanol peaks further decreased, while ethoxylation and siloxane derivatization increased. In all other products and aging conditions no silanols were traced and formation of small- and large-size MPTMS derivatives was evident. Apart from the 10-MDP molecule, phosphorous impurities were identified in all RE specimens (2–5%), which after AG reached a maximum value of 15% (MBP). MIR analysis showed siloxane formation in all products, regardless the presence of free silanols (t1), which further increased at t24 especially in CLB, GMP and MBP. SignificanceMPTMS silanols are very sensitive to mild thermal aging. Incorporation of MPTMS in the same vials with adhesive and conventional methacrylate monomers, results in derivatization with no detectable silanols, even in fresh materials. The condensates formed may induce additional siloxane formation due to residual activity, which greatly varies among the materials tested. These may have a detrimental effect on MPTMS silanol chemisorption and bonding capacity.

Photo-stability study of a solution-processed small molecule solar cell system: correlation between molecular conformation and degradation

Solution-processed organic small molecule solar cells (SMSCs) have achieved efficiency over 11%. However, very few studies have focused on their stability under illumination and the origin of the degradation during the so-called burn-in period. Here, we studied the burn-in period of a solution-processed SMSC using benzodithiophene terthiophene rhodamine:[6,6]-phenyl C71 butyric acid methyl ester (BTR:PC71BM) with increasing solvent vapour annealing time applied to the active layer, controlling the crystallisation of the BTR phase. We find that the burn-in behaviour is strongly correlated to the crystallinity of BTR. To look at the possible degradation mechanisms, we studied the fresh and photo-aged blend films with grazing incidence X-ray diffraction, UV–vis absorbance, Raman spectroscopy and photoluminescence (PL) spectroscopy. Although the crystallinity of BTR affects the performance drop during the burn-in period, the degradation is found not to originate from the crystallinity changes of the BTR phase, but correlates with changes in molecular conformation – rotation of the thiophene side chains, as resolved by Raman spectroscopy which could be correlated to slight photobleaching and changes in PL spectra.