Butyric Acid Methyl Ester Research Articles

Unveiling Nanoscale Ordering in Amorphous Semiconducting Polymers Using Four-Dimensional Scanning Transmission Electron Microscopy.

We present four-dimensional (4D) scanning transmission electron microscopy (STEM) analysis to obtain a high level of detail regarding the nanoscale ordering within largely disordered organic semiconducting polymers. Understanding nanoscale molecular ordering in semiconducting polymers is crucial due to its connection to the materials' important properties. However, acquiring such information in a spatially localized manner has been limited by the lack of a nanoscale experimental probe, weak signal from ordering, and radiation damage to the sample. By collecting nanodiffraction patterns with a high dynamic range pixelated detector, we acquired statistically robust, high signal-to-noise ratio diffraction patterns from semiconducting organic materials, including poly(3-hexylthiophene-2,5-diyl) (P3HT), P3HT/[6,6]-phenyl C61 butyric acid methyl ester, and indacenodithiophene-co-benzothiadiazole (IDTBT), which largely have disordered structures. Real-space images of the ordered domains were reconstructed from the 4D-STEM data set for a variety of scattering vectors and in-plane angles to capture the different molecular stacking distances and their in-plane orientation. These were then analyzed to obtain the average size of the ordered domains within the sample. Such measurements were arranged in a two-dimensional (2D) histogram, which showed a direct relationship between the type and size of molecular ordering. Complementary analyses, such as intensity variance and angular correlation, were applied to obtain ordering and symmetry information. These analyses enabled us to directly characterize the alkyl and π-π stacking of P3HT, as well as the fullerene domains caused by donor segregation in the P3HT sample. Furthermore, the analysis also captured changes in the P3HT domains when the fullerenes are incorporated. Lastly, IDTBT showed a much lesser degree of ordering without much disinclination between the domains within the 2D histogram. The 4D-STEM analysis that we report here unveils new details of molecular ordering that can be used to optimize the properties of this important class of materials.

Elucidating the hysteresis effect in printed flexible perovskite solar cells with SnO2 quantum dot- and PCBM-based electron transport layers

Recently, flexible perovskite solar cells (FPSCs) fabricated using solution-processed printing techniques have garnered significant attention. However, challenges remain in achieving cost-effective, scalable manufacturing under ambient conditions and ensuring stable, efficient devices. This study focuses on fabricating printed FPSCs using the slot-die coating technique and examines the impact of SnO2 quantum dot (QD) and (6,6)-Phenyl C61 butyric acid methyl ester (PCBM) based electron transport layers (ETLs) on device performance and hysteresis. Experimentally results show that SnO2 QD-based devices exhibited favorable photovoltaic properties but significant hysteresis compared to PCBM-based devices. Numerical simulations have shown that the hysteresis effect in devices is influenced not only by the higher concentration of mobile ions in the perovskite layer of PCBM-based devices compared to SnO2 QD-based devices, but also by the more effective redistribution of these ions during forward and reverse J-V scans. The results provide insights into the behavior of printed FPSCs with different ETLs, contributing to the development of high-performance, hysteresis-free printed FPSCs.

Influence of Aluminum Pillar Nanostructures on Thin‐Film Organic Solar Cells

This study explores the application of pillar nanostructures in organic solar cells (OSCs). The aluminum pillar nanostructures (AlPNSs) are fabricated on an active layer surface comprising of a blend poly(3‐hexylthiophene‐2,5‐diyl) and [6,6]‐phenyl C61 butyric acid methyl ester using nanoimprinting. Aluminum back electrodes are formed, resulting in AlPNSs with an imprinted pattern height of 60 ± 6 nm and a pitch of 212 ± 49 nm. Atomic force microscope images and current density versus voltage curves are obtained for the fabricated devices, both with and without AlPNSs. The results indicate a solar cell efficiency increase of 15.16% in the AlPNS OSCs compared to the reference cells. To investigate the role of AlPNSs in the enhancement, impedance spectroscopy, incident photon‐to‐current efficiency, UV–Vis reflection spectroscopy, and finite‐difference time‐domain simulations are performed for the both devices. The results demonstrate that the combination of propagating surface plasmon resonance and light‐trapping properties due to AlPNSs significantly enhances the overall optical performance. This research provides new insights into the potential of imprinted nanostructures for enhancing OSC performance, including their plasmonic and optical characteristics.

Bulk Heterojunction Solar Cell using Ru Dye Attached PCBM

Ru dye (Z-907) is a crucial photosensitizing material in dye-sensitized solar cells (DSSCs). To enhance the utilization of Ru dye’s photosensitizing properties in bulk heterojunction solar cells, a method was developed to synthesize phenyl-C61- butyric acid methyl ester (PCBM) nanoparticles that are chemically linked to Ru dye. PCBM contains a methoxy (−OCH3) group, whereas Ru dye incorporates a carboxyl group (−COOH) within its molecular structure. By exploiting these complementary functional groups, a successful bond between Ru dye and PCBM was established through an anhydride functional group. The coupling of PCBM with Ru dye results in a modification of the energy levels, yielding lower LUMO (3.8 eV) and HOMO (6.1 eV) levels, compared with the LUMO (3.0 eV) and HOMO (5.2 eV) levels of Ru dye alone. This configuration potentially facilitates efficient electron transfer from Ru dye to PCBM, alongside promoting hole transfer from Ru dye to the conducting polymer. Consequently, the bulk heterojunction solar cells incorporating this Ru dye-PCBM configuration demonstrate superior performance, with an open circuit voltage (Voc) of 0.62 V, short circuit current (Jsc) of 0.63 mA cm−2, fill factor (FF) of 65.6%, and a photovoltaic conversion efficiency (η) of 0.25%.

Interface passivation using diketopyrrolopyrrole‐oligothiophene copolymer to improve the performance of perovskite solar cells

AbstractThe unprecedented increase in power conversion efficiency (PCE) of low‐cost organo‐inorganic halide perovskite solar cells (OIHPSCs) toward its Shockley‐Queisser limit intriguingly has prompted researchers to investigate the disadvantages of these devices. The issue of operational stability is the main hurdle challenging the way forward for commercialization. To address this, various engineering processes like composition, additives, anti‐solvents, bulk and interface passivation, and deposition techniques have been widely applied to manage both extrinsic and intrinsic factors that induce degradation of the OIHPSCs. In this work, we employed interface passivation, which is an efficient approach to reduce nonradiative recombination. An ultrathin layer of electron donor diketopyrrolopyrrole‐oligothiophene copolymer (DPP860) was applied as an interface passivator between the photoactive layer and [6,6]‐phenyl C61 butyric acid methyl ester (PCBM). The role of the interface passivation on optoelectronic properties of the OIHPSCs was assessed using current density versus voltage (J‐V) characteristics, photoluminescence spectroscopy and time‐resolved photoluminescence spectroscopy. The findings show devices treated with DPP860 exhibit enhanced current density (Jsc) and fill factor, attributing for suppressed nonradiative recombination. Moreover, it shows relative improvement in the stability of the device. The results of this finding reveal that using oligothiophene copolymer can enhance the photovoltaic performance and the stability of inverted OIHPSCs in the ambient environment.

Influence of the electron transport layer coating technique on sputter damage and its curing in inverted semi-transparent perovskite solar cells without protective buffer layer

In semi-transparent perovskite solar cells (PSCs) comprising a sputtered top electrode, the minimisation of detrimental sputter damage and/or its curing by post-processing treatment is essential to reach high efficiencies. In this work, we investigate the influence of sputter damage and post-deposition annealing steps for different electron transport layers (ETLs) in PSCs without the need of a protective buffer layer such as tin oxide deposited by atomic layer deposition. We compare solution-processed 6,6-Phenyl C61 butyric acid methyl ester (PCBM) to thermally evaporated C60, each in combination with a bathocuproine (BCP) layer deposited by spin coating or thermal evaporation including a thickness variation. In general, we find that C60 is more resilient against sputter damage and thus C60-based cells show higher as-grown power conversion efficiencies (PCEs). Post-deposition annealing of the complete cell stack increases the PCE further to values > 16 % on 0.5 cm2 active area. However, we observe that the remaining solvent in the spin-coated PCBM layer is highly beneficial for the curing of the sputter damage during post-deposition annealing and we achieve even higher PCEs for cells incorporating solution-processed PCBM with up to > 18 % on 0.5 cm2. We show an alternative way to reach high efficiency semi-transparent perovskite solar cells without using thermally evaporated C60 and/or a buffer layer like tin oxide deposited by atomic layer deposition (ALD).

Fluorinated organic ammonium salt passivation for high-efficiency and stable inverted CsPbI2Br perovskite solar cells.

All-inorganic CsPbI2Br inverted perovskite solar cells (PSCs) have drawn increasing attention because of their outstanding thermal stability and compatible process with tandem cells. However, relatively low open circuit voltage (Voc) has lagged their progress far behind theoretical limits. Herein, we introduce phenylmethylammonium iodide and 4-trifluoromethyl phenylmethylammonium iodide (CFPMAI) on the surface of a CsPbI2Br perovskite film and investigate their passivation effects. It is found that CFPMAI with a -CF3 substituent significantly decreases the trap density of the perovskite film by forming interactions with the under-coordinated Pb2+ ions and effectively suppresses the non-radiative recombination in the resulting PSC. In addition, CFPMAI surface passivation facilitates the optimization of energy-level alignment at the CsPbI2Br perovskite/[6,6]-phenyl C61 butyric acid methyl ester interface, resulting in improved charge extraction from the perovskite to the charge transport layer. Consequently, the optimized inverted CsPbI2Br device exhibits a markedly improved champion efficiency of 14.43% with a Voc of 1.12V, a Jsc of 16.31 mA/cm2, and a fill factor of 79.02%, compared to the 10.92% (Voc of 0.95V) efficiency of the control device. This study confirms the importance of substituent groups on surface passivation molecules for effective passivation of defects and optimization of energy levels, particularly for Voc improvement.

Effective surface passivation for stable and high-performance inverted CsPbI2Br perovskite solar cells with efficiency over 15%

Inverted CsPbI2Br perovskite solar cells (PSCs) still suffer from substantially non-radiative recombination losses at the perovskite interface, which limits the future advancement of CsPbI2Br perovskite-based single- and multi-junction photovoltaic cells. Interfacial defect passivation of perovskite films is an effective approach for enhancing the performance of PSCs. In this study, we introduce thiophene halide salts with different side groups on the surface of CsPbI2Br films to passivate the inorganic perovskite film and investigate their passivation effects. Our studies show that the 2-thiophenemethylammonium iodide (TM) passivator with –CH2NH3I side group effectively mitigates the trap density of the perovskite film by forming coordination bonding with Pb2+ ions, thus significantly inhibiting the non-radiative recombination in the resulting PSC. In addition, after the TM treatment, the better energy-level alignment between the CsPbI2Br/[6,6]-Phenyl C61 butyric acid methyl ester (PCBM) interface is achieved, thus enhancing the charge extraction from perovskite to the charge transport layer. The resulting inverted CsPbI2Br device demonstrates a significantly enhanced champion efficiency of 15.07% with a Voc of 1.16 V, Jsc of 16.42 mA/cm2, and FF of 79.11%, compared to the 11.19% efficiency of the control device, and maintains >97% of the initial efficiency after being stored for over 1700 h in N2 atmosphere. This work confirms the importance of substituent groups on surface passivation molecules for effective passivation of defects and optimization of energy levels, particularly for Voc improvement.

Toward Low-Voltage and High-Sensitivity Direct X-ray Detectors Based on Thick Bulk Heterojunction Organic Device.

Organic semiconducting materials are promising for the fabrication of flexible ionizing radiation detectors for imaging because of their tissue equivalence, simple large-scale processing, and mass production. However, it is challenging to achieve high-sensitivity detection for organic direct detectors prepared by low-cost solution processing because of the compromise between thickness and carrier transport. In this study, high-performance organic direct X-ray detectors were fabricated by building a micrometer-thick bulk heterojunction (BHJ) using poly(3-hexylthiophene-2,5-diyl) (P3HT):(6,6)-phenyl c71 butyric acid methyl ester. A 5 μm BHJ film was fabricated by drop-casting and enhanced crystallization of P3HT using binary solvents and high-boiling-point additives to improve the charge carrier mobility. Furthermore, this organic direct X-ray detector has a sensitivity of >654.26 μC Gyair s-1 and a self-powered response. Because of the architecture of the thick active layer and the energy cascade in this diode detector, it has a very low dark current of 46.26 pA at -2 V. A fast and efficient approach was developed for fabricating thick, highly mobile organic BHJ films for high-performance direct X-ray detectors. It has great potential for application in a new generation of flexible and portable large-area flat-panel detectors.

Insulating 6,6-Phenyl-C61-butyric Acid Methyl Ester on Transition-Metal Dichalcogenides: Impact of the Hybrid Materials on the Optical and Electrical Properties.

In this study we develop a strategy to insulate 6,6 -Phenyl C61 butyric acid methyl ester (PCBM) on the basal plane of transition metal dichalcogenides (TMDs). Concretely single layers of MoS2, MoSe2, MoTe2, WS2, WSe2 and WTe2 and ultrathin MoO2 and WO2 were grown via chemical vapor deposition (CVD). Then, the thiol group of a PCBM modified with cysteine reacts with the chalcogen vacancies on the basal plane of TMDs, yielding PCBM-MoS2, PCBM-MoSe2, PCBM-WS2, PCBM-WSe2, PCBM-WTe2, PCBM-MoO2 and PCBM-WO2. Afterwards, all the hybrid materials were characterized using several techniques, including XPS, Raman spectroscopy, TEM, AFM, and cyclic voltammetry. Furthermore, PCBM causes a unique optical and electrical impact in every TMDs. For MoS2 devices, the conductivity and photoluminescence (PL) emission achieve a remarkable enhancement of 1700 % and 200 % in PCBM-MoS2 hybrids. Similarly, PCBM-MoTe2 hybrids exhibit a 2-fold enhancement in PL emission at 1.1 eV. On the other hand, PCBM-MoSe2, PCBM-WSe2 and PCBM-WS2 hybrids exhibited a new interlayer exciton at 1.29-1.44, 1.7 and 1.37-154 eV along with an enhancement of the photo-response by 2400, 3200 and 600 %, respectively. Additionally, PCBM-WTe2 and PCBM-WO2 showed a modest photo-response, in sharp contrast with pristine WTe2 or WO2 which archive pure metallic character.

Effect of Anode Interfacial Modification by Self-Assembled Monolayers on the Organic Solar Cell Performance.

A series of self-assembled monolayer (SAM)-based benzoic acid derivatives such as 4-[5'-phenyl-2,2'-bitien-5-yl] benzoic acid (ZE-Ph), 4-[5'-(4-fluorophenyl)-2,2'-bitien-5-yl]benzoic acid (ZE-1F), and 4-[5'-(3,5-difluorophenyl)-2,2'-bitien-5-yl]benzoic acid (ZE-2F) were synthesized to use an interlayer between an ITO electrode and a MoO3 thin film layer in an organic solar cell (OSC) having poly-3 hexylthiophene (P3HT): [6,6]-phenyl C61 butyric acid methyl ester (PC61BM) blend. The work function and surface wetting properties of the ITO were tuned by SAM molecules. The power conversion efficiency of fabricated OSC devices was improved compared to that of the control device from 1.93 to 2.20% and 2.22% with ZE-Ph and ZE-1F-modified ITO electrodes, respectively. The short-circuit current density (Jsc) was increased from 6.16 to 7.10 mA/cm2 and 6.94 mA/cm2 with control, ZE-Ph, and ZE-1F-modified solar cells, respectively. The increase in short-circuit current density (Jsc) shows that the hole-transporting properties between ITO and MoO3 were improved by the use of ZE-Ph and ZE-1F compared with that of the ITO/MoO3 electrode configuration. The open-circuit voltage (Voc) of the SAM-modified ITO-based devices was also improved compared with the Voc of unmodified ITO-based devices. These results show that using a monolayer as an interlayer in OSCs is an important strategy to improve the performance of OSCs. All the device parameters were characterized by Kelvin probe force microscopy, cyclic voltammetry, contact angle, and I-V measurements.

Enhanced Efficiency and Stability of Inverted CsPbI2Br Perovskite Solar Cells via Fluorinated Organic Ammonium Salt Surface Passivation.

All-inorganic perovskite solar cells (PSCs) have recently received increasing attention due to their outstanding thermal stability. However, the performance of these devices, especially for the devices with a p-i-n structure, is still inferior to that of the typical organic-inorganic counterparts. In this study, we introduce phenylammonium iodides with different side groups on the surface of the CsPbI2Br perovskite film and investigate their passivation effects. Our studies indicate that the 4-trifluoromethyl phenylammonium iodide (CFPA) molecule with the -CF3 side group effectively decreases the trap density of the perovskite film by forming interactions with the undercoordinated Pb2+ ions and significantly inhibits the nonradiative recombination in the derived PSC, leading to an enhanced open-circuit voltage (Voc) from 0.96 to 1.10 V after passivation. Also, the CFPA post-treatment enables better energy-level alignment between the conduction band minimum of CsPbI2Br perovskite and [6,6]-phenyl C61 butyric acid methyl ester, thereby enhancing the charge extraction from the perovskite to the charge transport layer. These combined benefits result in a significant enhancement of the power conversion efficiency from 11.22 to 14.37% for inverted CsPbI2Br PSCs. The device without encapsulation exhibits a degradation of only ≈4% after 1992 h in a N2 glovebox.

Equal proportion of donor/acceptor active layer for reduced dark current in visible organic photodiode

The present study investigates a visible organic photodiode with low dark current of 0.002 mA/cm2. The active layer is a bulk heterojunction (BHJ) binary blended film composed of Poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) as a donor material along with (6,6)-Phenyl C71 butyric acid methyl ester (PC71BM) as an acceptor material. The device was fabricated using a facile spin coating technique with the structure of ITO/PEDOT:PSS/PCDTBT:PC71BM/Al. The composition of PCDTBT and PC71BM has significantly improved the absorption of the UV–visible spectrum, especially between 300 and 650 nm. The optimized device of the blended film (1:1 blend ratio) showed a good photoresponsivity of 114 mA/W, with a fast response-recovery time of 733 ms and 597 ms, respectively. It is found that the specific detectivity obtained is 1.79×109 Jones and external quantum efficiency (EQE) is 29.13 %. The results manifested the optimized device can be employed in the fabrication of a cost-effective and highly sensitive visible organic photodiode.

Highly efficient lead-free ethyl ammonium substituted perovskite solar cell simulated using SCAPS 1D

This computational study investigated a lead (Pb)-free ethyl ammonium (EA) substituted ethylenediamine (EDA) based ((FA0.9EA0.1)0.98EDA0.01SnI3) perovskite solar cell (PSC) using the solar cell capacitance one-dimensional simulator (SCAPS 1D). The initial device schematic comprised ((FA0.9EA0.1)0.98EDA0.01SnI3) based perovskite as an absorber layer with copper (I) oxide (Cu2O) and [6,6] phenyl-C61 butyric acid methyl ester (PCBM) as hole and electron transport layers, where the device efficiency was 21.87%. The impacts of numerous electron transport layers (ETLs) and hole transport layers (HTLs) were also examined. The charge transport layers were optimized based on their energy levels and according to the relationship between the built-in potential (Vbi) and the open-circuit voltage (VOC). Numerical simulations showed that to circumvent the Vbi loss, the valence band (VB) maximum of HTL (EVB_HTL) should not be lower than the VB for perovskite (PVK) (EVB_PVK) for the appropriate selection of HTLs. Correspondingly, for the suitable selection of ETLs, the conduction band (CB) minimum of ETL (ECB_ETL) and the front contact should not be greater than the CB minimum for PVK (ECB_PVK). Therefore, the optimized ETLs and HTLs were obtained as zinc oxysulfide and copper (II) phthalocyanine, respectively, where the device's efficiency increased up to 22.36%. The effect of the thickness of the EDA-based PSCs was also examined and the optimized thickness was obtained as 1.1 μm, where the device's efficiency increased to 24.42%. This improvement in the performance of the device indicates that EA substituted EDA-based ((FA0.9EA0.1)0.98EDA0.01SnI3) PSC is a promising alternative for use in Pb-free PSCs.

The novel n-channel liquid crystal organic field effect transistor (LC-n-OFET): A promising technology for low-power electronics

In this study, a novel n-channel liquid crystal organic field effect transistor (LC-n-OFET) was fabricated using a mixture of E7 nematic liquid crystal (NLC) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) in an OFET cell. The LC-n-OFET performance was investigated regarding dielectric properties, UV illumination sensitivity, and channel length dependence. Output and transfer current-voltage (I–V) characteristics were measured to evaluate the electrical properties in dark and under UV illumination for varying channel lengths. Additionally, the dielectric characteristics of the LC-n-OFET were determined along with the capacitance-frequency response (Ci-f), threshold voltage (VTh), field-effect mobility (μFET), and on/off current ratio (Ion/off) as a function of UV illumination intensity and channel length changes. Electrical measurements showed the Ion/off current ratio is inversely proportional to channel length but directly proportional to UV intensity. Meanwhile, the threshold voltage (VTh) and mobility (μFET) increased with longer channel length and higher light intensity. Overall, the novel LC-n-OFET exhibited promising performance with low VTh, high μFET, and large Ion/off.

Scalable Solution-Processed Hybrid Electron Transport Layers for Efficient All-Perovskite Tandem Solar Modules.

All-perovskite tandem solar cells offer the potential to surpass the Shockley-Queisser (SQ) limit efficiency of single-junction solar cells while maintaining the advantages of low-cost and high-productivity solution processing. However, scalable solution processing of electron transport layer (ETL) in p-i-n structured perovskite solar subcells remains challenging due to the rough perovskite film surface and energy level mismatch between ETL and perovskites. Here, scalable solution processing of hybrid fullerenes (HF) with blade-coating on both wide-bandgap (≈1.80 eV) and narrow-bandgap (≈1.25 eV) perovskite films in all-perovskite tandem solar modules is developed. The HF, comprising a mixture of fullerene (C60 ), phenyl C61 butyric acid methyl ester, and indene-C60 bisadduct, exhibits improved conductivity, superior energy level alignment with both wide- and narrow-bandgap perovskites, and reduced interfacial nonradiative recombination when compared to the conventional thermal-evaporated C60 . With scalable solution-processed HF as the ETLs, the all-perovskite tandem solar modules achieve a champion power conversion efficiency of 23.3% (aperture area = 20.25 cm2 ). This study paves the way to all-solution processing of low-cost and high-efficiency all-perovskite tandem solar modules in the future.

Facile fabrication of conductive graphitic carbon films as transparent electrodes in organic solar cells by ion beam irradiation of polystyrene films and carbonization

Conductive graphitic carbon films were fabricated from insulating polystyrene (PS) by ion beam irradiation and subsequent thermal treatment, and used as a transparent anode for organic solar cells (OSCs). Analyses of optical and chemical properties revealed that the thermally resistant oxidized carbon clusters in the PS precursors (spin-coated on quartz) were efficiently generated by ion beam irradiation at a fluence of 2 x 1016 ions/cm2, and transformed to graphitic carbon thin films through high-temperature treatment. The graphitic carbon films exhibited thickness-dependent conductivity (the highest conductivity of 374 S/cm), while their work function (5.20 eV) and surface roughness (0.560–0.596 nm) were unaffected by the thickness of the films. Furthermore, the introduction of the 10.2 nm-thick graphitic carbon films into poly(3-hexylthiophene) (P3HT): [6,6]-phenyl-C61 butyric acid methyl ester (PCBM)-based OSCs resulted in a power conversion efficiency (PCE) of 1.40%, demonstrating the feasibility of using the graphitic carbon films as transparent electrodes.

Tissue Equivalent Curved Organic X-ray Detectors Utilizing High Atomic Number Polythiophene Analogues.

Organic semiconductors are a promising material candidate for X-ray detection. However, the low atomic number (Z) of organic semiconductors leads to poor X-ray absorption thus restricting their performance. Herein, the authors propose a new strategy for achieving high-sensitivity performance for X-ray detectors based on organic semiconductors modified with high -Z heteroatoms. X-ray detectors are fabricated with p-type organic semiconductors containing selenium heteroatoms (poly(3-hexyl)selenophene (P3HSe)) in blends with an n-type fullerene derivative ([6,6]-Phenyl C71 butyric acid methyl ester (PC70 BM). When characterized under 70, 100, 150, and 220kVp X-ray radiation, these heteroatom-containing detectors displayed a superior performance in terms of sensitivity up to 600 ± 11nCGy-1 cm-2 with respect to the bismuth oxide (Bi2 O3 ) nanoparticle (NP) sensitized organic detectors. Despite the lower Z of selenium compared to the NPs typically used, the authors identify a more efficient generation of electron-hole pairs, better charge transfer, and charge transport characteristics in heteroatom-incorporated detectors that result in this breakthrough detector performance. The authors also demonstrate flexible X-ray detectors that can be curved to a radius as low as 2mm with low deviation in X-ray response under 100 repeated bending cycles while maintaining an industry-standard ultra-low dark current of 0.03 ± 0.01pAmm-2 .

Efficient and Stable Air-Processed Ternary Organic Solar Cells Incorporating Gallium-Porphyrin as an Electron Cascade Material.

Two gallium porphyrins, a tetraphenyl GaCl porphyrin, termed as (TPP)GaCl, and an octaethylporphyrin GaCl porphyrin, termed as (OEP)GaCl, were synthesized to use as an electron cascade in ternary organic bulk heterojunction films. A perfect matching of both gallium porphyrins' energy levels with that of poly(3-hexylthiophene-2,5-diyl) (P3HT) or poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) polymer donor and the 6,6-phenyl C71 butyric acid methyl ester (PCBM) fullerene acceptor, forming an efficient cascade system that could facilitate electron transfer between donor and acceptor, was demonstrated. Therefore, ternary organic solar cells (OSCs) using the two porphyrins in various concentrations were fabricated where a performance enhancement was obtained. In particular, (TPP)GaCl-based ternary OSCs of low concentration (1:0.05 vv%) exhibited a ~17% increase in the power conversion efficiency (PCE) compared with the binary device due to improved exciton dissociation, electron transport and reduced recombination. On the other hand, ternary OSCs with a high concentration of (TPP)GaCl (1:0.1 vv%) and (OEP)GaCl (1:0.05 and 1:0.1 vv%) showed the poorest efficiencies due to very rough nanomorphology and suppressed crystallinity of ternary films when the GaCl porphyrin was introduced to the blend, as revealed from X-ray diffraction (XRD) and atomic force microscopy (AFM). The best performing devices also exhibited improved photostability when exposed to sunlight illumination for a period of 8 h than the binary OSCs, attributed to the suppressed photodegradation of the ternary (TPP)GaCl 1:0.05-based photoactive film.

In silico virtual screening for the identification of novel inhibitors against dihydrodipicolinate reductase (DapB) of Mycobacterium tuberculosis, a key enzyme of diaminopimelate pathway.

Tuberculosis (TB) caused by Mycobacterium tuberculosis (M. tb) is one of the most devastating infectious diseases afflicting a large number of human lives. In spite of the availability of several drugs for treating TB, emergence of drug-resistant strains of the pathogen has made treatment and eradication of TB a challenging task. Hence, there is an imperative need for new intervention strategies to target M. tb. The enzymes of the diaminopimelate pathway, involved in lysine biosynthesis as well as in cell wall biosynthesis, have been considered as important anti-TB drug targets. One such enzyme is dihydrodipicolinate reductase (DapB), catalyzing the reduction of 2,3-dihydrodipicolinic acid to 2,3,4,5-tetrahydro-dipicolinic acid by utilizing NADH/NADPH as its cofactor. Here, we have generated an antisense knockdown mutant strain of dapB and demonstrated a crucial role of dapB in the in vitro and intracellular growth of M. tb. Further, in silico virtual screening was performed by employing a library of ~95,000 compounds for the identification of inhibitory molecules against DapB. The molecules with high docking scores were screened against the enzymatic activity of DapB to determine their IC50 values. Further, hit molecules that inhibited DapB were screened against the M. tb growth in broth culture and inside macrophages. The molecules exhibiting M. tb inhibition were also evaluated for their cytotoxicity against various mammalian cell lines. In summary, we have identified a lead molecule, B59, with an IC50 value of 11 µg/mL and MIC99 value of 20 µg/mL, which can be further optimized to develop potent inhibitory compounds against M. tb DapB. IMPORTANCE Non-compliance to lengthy antituberculosis (TB) treatment regimen, associated side effects, and emergence of drug-resistant strains of Mycobacterium tuberculosis (M. tb) emphasize the need to develop more effective anti-TB drugs. Here, we have evaluated the role of M. tb dihydrodipicolinate reductase (DapB), a component of the diaminopimelate pathway, which is involved in the biosynthesis of both lysine and mycobacterial cell wall. We showed that DapB is essential for the in vitro as well as intracellular growth of M. tb. We further utilized M. tb DapB, as a target for identification of inhibitors by employing in silico virtual screening, and conducted various in vitro screening assays to identify inhibitors with potential to inhibit DapB activity and in vitro and intracellular growth of M. tb with no significant cytotoxicity against various mammalian cell lines. Altogether, M. tb DapB serves as an important drug target and a hit molecule, namely, 4-(3-Phenylazoquinoxalin-2-yl) butanoic acid methyl ester has been identified as an antimycobacterial molecule in our study.