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Solar-chemical production is one of the most promising options for producing valuable chemicals from greenhouse gases. An economically attractive and industrially applicable solar-chemical production device not only requires catalyst and/or reactor design, but also auxiliary unit process design, process integration, and optimization. Herein, we report a state-of-the-art monolithic solar-chemical production device having 8.03% solar to CO conversion efficiency and 0.77 to 31.9% CO2 one path conversion. Since the monolithic device directly couples a photovoltaic cell and a CO2 electrolyzer, the power loss due to a current converter can be avoided. According to the solar-chemical production device, a comprehensive process design accounting for CO2 to CO conversion, unreacted CO2 separation, and recycling structure is provided. The process model shows good agreement with experimental data for CO2 conversion in the electrolyzer. A process level techno-economic evaluation and a comprehensive review are also presented to highlight the current state and the economic feasibility of the developed device. Thereafter, we provide a sensitivity analysis in terms of CO2 conversion, membrane cost, solar to chemical efficiency, and current density necessary for economically profitable CO production. The equivalent CO sales cost from a 4 MW production plant is estimated to be $10.9 per kg and the corresponding carbon tax compensating for the price gap of the current market price is $6.6 per kg CO2. The sensitivity analysis demonstrates that >80 mA cm−2 current density or 22% CO2 conversion is desirable to effectively compete with the conventional CO production process.

In ongoing attempts to efficiently utilize abundant natural gas, there has been steady scientific and industrial interest in using an environmentally benign and inexpensive oxidant (dioxygen O2) for the direct catalytic oxidation of methane to oxygenate products under mild conditions. Here, we report the homogeneous bis(tetramethylammonium) tetrachlorocobaltate ([Me4N]2CoCl4)-catalyzed methane oxidation to methyl trifluoroacetate (MeTFA) with dioxygen O2 in trifluoroacetic acid (HTFA) media. [Me4N]2CoCl4 had the highest catalytic activity among previously reported homogeneous cobalt-based catalyst systems; the turnover of methane to MeTFA reached 8.26 molester molmetal−1h−1 at 180 °C. Results suggest that the ionic form of the catalyst makes the Co species more soluble in the HTFA media; consequently, an active catalyst form, [CoTFAxCly]2−, can form very rapidly. Furthermore, chloride anions dissociated from CoCl42− appear to suppress oxidation of the solvent HTFA, thereby driving the reaction toward methane oxidation. The effects of reaction time, catalyst concentration, O2 and methane pressure, and reaction temperature on MeTFA production were also investigated.

Although chloride-ligated Pt compounds like (bpym)PtCl 2 , K 2 PtCl 4 , and (DMSO) 2 PtCl 2 has been reported to be highly active catalysts for the methane oxidation to methyl bisulfate (MBS) in oleum media, their applications is hampered by the catalyst deactivation to PtCl 2 . In this study, we investigated Pt black catalyzed methane oxidation, which has no ligand. A MBS yield of 82.1% with a selectivity of 96.5% was obtained at a catalyst loading of 1.6 mM at 180 °C, which proved the highest catalytic activity of Pt-black for this reaction. The reaction was thought to proceed by the dissolved Pt species, and no deactivation was observed during four consecutive experiments. However, at a concentration of over 30 mM, MBS yield fell due to the decomposition of MBS to CO 2 on the surface of heterogeneous Pt(0). Vacuum distillation experiments showed the potential for isolating MBS from the oxidation product mixture as a major component.

SO2 absorption behaviours of N,N-dimethylaniline (DMA), N,N-diethylaniline (DEA), N,N-dibutylaniline (DBA), and N-methyldiphenylamine (MDPA) — were investigated in dry and wet conditions. DMA showed the highest SO2 absorption capacity of 1.5 molSO2 molAbsorbent−1 in dry condition, while DBA showed the highest capacity of 1.75 molSO2 molAbsorbent−1 in wet condition. Raman analyses revealed that anilines captured SO2 by forming charge transfer complexes in dry condition and the interaction between SO2 and aniline decreased as the steric hindrance of alkyl aniline increased. In contrast, bisulfite-based acid-base salt was formed in the presence of water, and the capacity increased with an increasing basicity of the alkyl aniline.

In this study, catalytic dehydrogenation of formic acid into H2/CO2 using half-sandwich Rh(III)/Ir(III) catalysts immobilized on variable dimensions of bipyridine-based covalent triazine frameworks (bpy-CTFs) has been described for the first time with a highest initial turnover frequency of 7930 h−1. A systematic study on the influence of the central metal cation (Rh vs. Ir), CTF architectures and amount of metal loadings on the CTF is presented.

To attain power generation with body heat, the thermal resistance matched design of the thermoelectric generator was the principal factor which was not critical in the case of thermoelectric generator for the waste heat generation. The dimension of thermoelectric legs and the number of thermoelectric leg-pairs dependent output power performances of the thermoelectric generator on the human wrist condition was simulated using 1-dimensional approximated heat flow equations with the temperature dependent material coefficients of the constituent materials and the dimension of the substrate. With the optimum thermoelectric generator design, thermoelectric generator modules were fabricated by using newly developed fabrication processes, which is mass production possible. The electrical properties and the output power characteristics of the fabricated thermoelectric modules were characterized by using a home-made test set-up. The output voltage of the designed thermoelectric generator were a few tens of millivolts and its output power was several hundreds of microwatts under the conditions at the human wrist. The measured output voltage and power of the fabricated thermoelectric generator were slightly lower than those of the designed thermoelectric generator due to several reasons.

Direct carbonylation of methanol into methyl acetate and acetic acid using Rh-based heterogeneous catalysts is of great interest due to their effective levels of activity and stability. Here, a Rh-based molecular catalyst heterogenized on a charged 1,3-bis(pyridyl)imidazolium-based covalent triazine framework (Rh-bpim-CTF) was synthesized and characterized to have a single-site distribution of metal molecular species throughout the support by its ligation to abundant N atom sites. Methanol carbonylation was performed using the Rh-bpim-CTF catalyst in a plug-flow reaction in the gas phase, affording a turnover frequency of up to 3693 h−1 and a productivity of 218.9 mol kg−1 h−1 for acetyl products with high stability.

As part of an effort to prepare a refrigerant with zero ozone depletion potential (ODP) and with a low global warming potential (GWP), the catalytic dehydrofluorination of 1,1,1,2,3-tetrafluoropropane (HFC-245eb) is performed to produce 2,3,3,3-tetrafluoropropene (HFO-1234yf). Cr2O3 prepared by the sol-gel method (Cr2O3(SG)) exhibits good catalytic activity attributable to the formation of surface chromium oxyfluoride, which exhibits better catalytic activity with high-valent chromium and a larger fluorine content. The formation of chromium oxyfluoride from chromium oxide is achieved by in-situ fluorination in the early stage of dehydrofluorination, avoiding the conventional fluorination method using toxic HF.

Background Familial IBD may have its own signatures with respect to host genetic variants and/or gut microbiome. However, available data focussing on this topic is still limited, particularly for Asian patients with familial IBD. We aimed to investigate the possible host genetic and gut microbial signatures in familial IBD through a combined analysis of genomic and metagenomic profiles. Methods All patients were affiliated with a prospectively recruited cohort of patients with IBD (NCT03589183) and met the diagnostic criteria of Crohn’s disease (CD) or ulcerative colitis (UC). We constructed a unique family cohort comprising ≥2 affected individuals with familial IBD and ≥1 their unaffected, healthy first-degree relative (FDR) in each family. Whole-exome sequencing for rare variants followed by a genome-wide single-nucleotide polymorphism analysis for common variants was performed. A polygenic risk score (PRS) was calculated separately in Crohn’s disease (CD), ulcerative colitis (UC) or IBD. Gut microbial community was analysed by 16s rRNA sequencing of stool samples. Results Eight Korean families comprising 16 with familial IBD (12 concordant IBD, 4 discordant IBD) and 9 FDRs were included for analysis. Whole-exome sequencing identified four family-specific candidate genes (LAMA5, MYO15B, TTN, and WDR66) with rare missense variants that were transmitted preferentially to the affected FDRs in at least ≥3 families (Figure 1). An in silico analysis identified the deleterious effect of the identified variants on the gene products including LAMA5 (SIFT = 0, PolyPhen-2 = 0.72). The patients with CD, but not those with UC, had a significantly higher mean PRS than controls (PRS = 2.137 vs. 0.742, p-value = 0.030). Metagenomic sequencing revealed significant differences in α- and β-diversity of gut microbiota among the patients with CD, those with UC, and unaffected FDRs (all p < 0.05), showing lower microbial richness in the patients with familial IBD (p = 0.02). In various taxonomic levels, compared with unaffected FDRs, the patients with familial IBD showed the significantly differential abundance of several gut bacteria (all corrected p < 0.05; Figure 2). Conclusion Family-specific host genetic and gut microbial signatures have a beneficial role in early-identification of familial IBD (NCT03515070).

A Study on Discharge Characteristics by Using MF and RF Power in Remote Dielectric Barrier Discharge D.J. Kima,b,∗, Y.K. Shim, H.J. Kim and J.G. Han Geniatech Inc., Room 810, Hanlla Sigma Valley, 545 Dunchun-daero, Jungwon-gu, Seongnam-si, Gyeonggi-do, South Korea CAPST, Sungkyunkwan University, 300 ChunChun-dong, Jangan-gu, Suwon 440-746, South Korea KIST, Center for Spintronics, Hwarangno 14-gil 5, Seongbuk gu, Seoul 136-791, South Korea

Molybdenum-doped porous bismuth vanadate (BiVO 4 ) nanostructures were successfully synthesized on a fluorine-doped tin oxide (FTO) substrate by a simple electrospinning technique. These nanostructures were used as the photoanode for solar water oxidation. Post hot-pressing treatment was crucial in improving the photocurrents of electrospun BiVO 4 by contributing to their adhesion on the substrate and for charge separation.

Background The primary aim of this study was to investigate the beneficial effect of exercise on completion rates of adjuvant treatment, which is one of the major prognostic factors among patients with locally advanced colorectal cancer after undergoing curative resection followed by adjuvant treatment. Methods We assigned patients who were scheduled to undergo adjuvant treatment (N = 39) to the exercise group or the control group in a 2:1 ratio in the order of enrollment. Patients completed questionnaires and underwent assessment of the outcome variables at the start of chemotherapy and upon completion of treatment. Results A five-fold lower possibility of dose adjustment in the exercise group compared to the control group was demonstrated (odds ratio, 0.188; P = 0.023; 95% confidence interval, 0.044–0.793). A significantly smaller proportion of the exercise group had grade 3 or 4 nausea (P = 0.018) and neurotoxicity (P = 0.024) symptoms. Muscle to fat ratios were significantly reduced in the control group (P = 0.039), but not in the exercise group (P = 0.742). Serum levels of leptin were significantly increased in the control group (P = 0.038), but not in the exercise group (P = 0.073). Serum levels of adiponectin were significantly increased in the exercise group (P = 0.026) but tended to be decreased in the control group with no statistical significance (P = 0.418). Conclusions Exercise training among patients with colorectal cancer was found to have a beneficial impact on adjuvant treatment completion rates and treatment-associated toxicities. This program was also shown to be beneficial to patients’ body compositions and serum levels of adipokines. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.

To achieve commercialization and widespread application of next-generation photovoltaics, it is important to develop flexible and cost-effective devices. Given this, the elimination of expensive transparent conducting oxides (TCO) and replacement of conventional glass substrates with flexible plastic substrates presents a viable strategy to realize extremely low-cost photovoltaics with a potentially wide applicability. To this end, we report a completely TCO-free and flexible dye-sensitized solar cell (DSSC) fabricated on a plastic substrate using a unique transfer method and back-contact architecture. By adopting unique transfer techniques, the working and counter electrodes were fabricated by transferring high-temperature-annealed TiO2 and Pt/carbon films, respectively, onto flexible plastic substrates without any exfoliation. The fabricated working electrode with the conventional counter electrode exhibited a record efficiency for flexible DSSCs of 8.10%, despite its TCO-free structure. In addition, the completely TCO-free and flexible DSSC exhibited a remarkable efficiency of 7.27%. Furthermore, by using an organic hole-transporting material (spiro-MeOTAD) with the same transfer method, solid-state flexible TCO-free DSSCs were also successfully fabricated, yielding a promising efficiency of 3.36%.

We present controls of nanomorphology of polymer:fullerene BHJ films via synthesis of a series of push–pull-type copolymers with various molar percentages of side chains terminated with o-dichlorobenzyl (DCBZ) groups. As the molar percentage of the DCBZ-containing repeat units increases, the miscibility of the polymers in the series with PC71BM increases with respect to that of the polymer (PTBBO) that does not contain DCBZ. In the optimal film morphology, which consists of a polymer containing 25 mol % DCBZ-terminated side chains in the electron-pull unit (PTBDCB25), the polymer/PC71BM interface area is sufficiently large for efficient charge separation and percolated pathways is present for efficient charge carrier transport. In contrast, the BHJ film prepared from PTBBO has smaller interfaces and larger PC71BM aggregates. Furthermore, the intermolecular interaction between PC71BM and DCBZ induced changes in the PC71BM’s electronic structure at the polymer:PC71BM interface, resulting in an increase of t...

Kesterite Cu2ZnSnSe4 (CZTSe) thin films prepared by the selenization of mechanochemically synthe- sized Cu2ZnSnS4 (CZTS) nanocrystal films are systematically investigated as a function of the annealing time in terms of the phase purity, microstructure, composition, and device characteristics. It is shown that selenization for an extended time does not cause a noticeable amount of Sn loss or segregation of Zn-rich layers. Thus, the prolonged annealing leads to improvements (reduction) in the shunt conductance, reverse saturation current, and diode ideality factor. However, it also leads to a deterioration of the series resistance, of which influence turned out to overwhelm all of the aforementioned positive effects on the device performance. As a consequence, the CZTSe solar cell exhibits its highest efficiency (5.43%) at the shortest annealing time (10 min). Impedance spectroscopy is demonstrated to be of good use in detecting the change in the back contact of CZTSe solar cells during annealing. The impedance spectra of the CZTSe solar cells are analyzed in association with the microstructures of the back-contact electrodes, demonstrating that the increase in the series resistance is attributed to the formation of the resistive MoSe2 layer.

We synthesized a series of push–pull-type copolymers by copolymerizing an electron-deficient diketopyrrolopyrrole with three electron-donating benzodithiophene (BDT) moieties. PDPPDTT, which incorporated a dithienothiophene (DTT), showed a higher power conversion efficiency (PCE) of 6.11% compared to 3.31% for the BDT-based polymer (PDPPBDT). PDPPDTBDT, which incorporated a dithienobenzodithiophene (DTBDT), also exhibited superior performance, with a PCE of 4.75% although this value was lower than that obtained for PDPPDTT. The presence of the DTT unit in the polymer backbone lowered the energy bandgap of the polymer and induced an optimal morphology in the polymer:PC71BM blend film, resulting in higher charge carrier generation. Furthermore, the effectively delocalized frontier orbitals of PDPPDTT enhanced intermolecular interactions between the polymer chains by favoring effective π–π stacking, which facilitated charge carrier transport. By contrast, PDPPDTBDT unexpectedly showed a low-crystallinity thi...

In this study, we demonstrated the effective morphological control of polymer:fullerene blends using three separate solvent systems: chloroform (CF), CF:1,8-diiodooctane (DIO), and CF:o-dichlorobenzene (ODCB). The polymer:fullerene blends are composed of two diketopyrrolopyrrole (DPP)-based polymers of P(DPP-alt-QT) and P(DPP-alt-DTBSe) and a fullerene derivative of [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM), i.e., P(DPP-alt-QT):PC71BM or P(DPP-alt-DTBSe):PC71BM. The CF:ODCB binary solvent exhibited the best photovoltaic performance among the three solvent systems for both polymer-based devices, although the CF:DIO also exhibited an improved performance compared to the CF system. By examining film morphology of the blend films, we found that the CF:ODCB enabled the most optimal nanoscale phase separation and the morphological features were strongly affected by the solubility of each material in the high boiling-point (BP) solvent. Specifically, the polymers have limited but slightly higher solubility in ODCB than in DIO, while the PC71BM molecules have a high solubility in both DIO and ODCB. Therefore, this work highlights that the optimally asymmetric solubility of each photoactive component in the high BP solvent is a critical factor to form the nanoscale, bicontinuous domains in the blend films and thereby to determine the performance of photovoltaic devices.

Highly efficient copper-zinc-tin-selenide (Cu2ZnSnSe4 ; CZTSe) thin-film solar cells are prepared via the electrodepostion technique. A metallic alloy precursor (CZT) film with a Cu-poor, Zn-rich composition is directly deposited from a single aqueous bath under a constant current, and the precursor film is converted to CZTSe by annealing under a Se atmosphere at temperatures ranging from 400 °C to 600 °C. The crystallization of CZTSe starts at 400 °C and is completed at 500 °C, while crystal growth continues at higher temperatures. Owing to compromises between enhanced crystallinity and poor physical properties, CZTSe thin films annealed at 550 °C exhibit the best and most-stable device performances, reaching up to 8.0 % active efficiency; among the highest efficiencies for CZTSe thin-film solar cells prepared by electrodeposition. Further analysis of the electronic properties and a comparison with another state-of-the-art device prepared from a hydrazine-based solution, suggests that the conversion efficiency can be further improved by optimizing parameters such as film thickness, antireflection coating, MoSe2 formation, and p-n junction properties.

We synthesized four polymers (pT3DPP-HD, pT3DPP-OD, pT2TTDPP-HD, and pT2TTDPP-OD) and characterized their photovoltaic properties as a function of the backbone planarity, alkyl side chain length, and film morphology. The polymers were donor–acceptor type low-band-gap (1.2–1.3 eV) polymers employing terthiophene (T3) or thiophene–thieno[3,2-b]thiophene–thiophene (T2TT) as the donor and 2,5-bis(2-hexyldecyl)pyrrolo[3,4-c]pyrrole-1,4-(2H,5H)-dione (DPP-HD) or 2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4-(2H,5H)-dione (DPP-OD) as the acceptor. The T2TT moiety in the polymer backbone is more planar than the T3; the OD moiety as the alkyl side chain ensured a higher solubility than the HD moiety. Polymer solar cells (PSCs) were fabricated, and their properties were characterized. The photoactive layer consisted of one of the four polymers and one of the fullerene derivatives (PC70BM or PC60BM). For a given fullerene derivative, the PCEs prepared with each of the four polymers were ordered according to pT3DP...

This work investigates the promotional roles of ZrO2 and ZnO for methanol synthesis on five Cu6Zn3.0-xZrxAl1 (x = 0.0, 0.5, 1.5, 2.5, 3.0) catalysts in the various CO2 feed composition. TOF decreased with an increase in x of Cu6Zn3.0-xZrxAl1 catalysts in the 5% CO2 feed, while TOF is maximized over Cu6Zn1.5Zr1.5Al1 in the 100% CO2 feed. Both the effects of Zn (reverse spillover) and Zr (additional reaction sites) in the vicinity of Cu promote the CO2 hydrogenation, maximizing the catalytic activity of Cu6Zn1.5Zr1.5Al1 in the 100% CO2 feed. The migration of hydrogen on ZrO2 can be limited in little surface hydroxyls in 5% CO2 feed, which can be a reason for the negative role of ZrO2 in the 5% CO feed. The promotional effect of ZrO2 on Cu/ZnO is important only for high CO2 feed more than 50% CO2.

Low bandgap polymers with dithienylquinoxaline moieties based on 6H-phenanthro[1,10,9,8-cdefg]carbazole were synthesized via the Suzuki coupling reaction. Alkoxy groups were substituted at two different positions on the phenyl groups of the quinoxaline units of these polymers: in the para-position (PPQP) and in the meta-position (PPQM). The two polymers showed similar physical properties: broad absorption in the range of 400–700 nm, optical bandgaps of ∼1.8 eV, and the appropriate frontier orbital energy levels for efficient charge transfer/separation at polymer/PC71BM interfaces. However, the PPQM solar cell achieved a higher PCE due to its higher Jsc. Our investigation of the morphologies of the polymer:PC71BM blend films and theoretical calculations of the molecular conformations of the polymer chains showed that the polymer with the meta-positioned alkoxy group has better miscibility with PC71BM than the polymer with the para-positioned alkoxy group because the dihedral angle of its phenyl group with respect to the quinoxaline unit is higher. This higher miscibility resulted in a polymer:PC71BM blend film with a better morphology and thus in a higher PCE. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 796–803

We demonstrate here that an improvement in the green density leads to a great enhancement in the photovoltaic performance of CuInSe2 (CISe) solar cells fabricated with Cu-In nanoparticle precursor films via colloidal solution deposition. Cold-isostatic pressing (CIP) increases the precursor film density by ca. 20%, which results in an appreciable improvement in the microstructural features of the sintered CISe film in terms of a lower porosity, a more uniform surface morphology, and a thinner MoSe2 layer. The low-band-gap (1.0 eV) CISe solar cells with the CIP-treated films exhibit greatly enhanced open-circuit voltage (V(OC), typically from 0.265 to 0.413 V) and fill factor (FF, typically from 0.34 to 0.55), compared to the control devices. As a consequence, an almost 3-fold increase in the average efficiency, from 3.0 to 8.2% (with the highest value of 9.02%), is realized. Diode analysis reveals that the enhanced V(OC) and FF are essentially attributed to the reduced reverse saturation current density and diode ideality factor. This is associated with suppressed recombination, likely due to the reduction in recombination sites at grain/air surfaces, intergranular interfaces, and defective CISe/CdS junctions. From the temperature dependences of V(OC), it is revealed that CIP-treated devices suffer less from interface recombination.

We fabricated metallic Cu–Zn–Sn (CZT) precursor thin films via electrochemical deposition from aqueous metal salt solution on Mo-coated soda-lime glass substrates, and the influence of the subsequent sulfurization condition on the morphology, composition and structure of the final Cu2ZnSnS4 (CZTS) thin films was investigated. A rapid thermal annealing equipment was used for a systematic control of the sulfurization process parameters. The as-deposited films are composed of binary metallic alloys, which can be converted to the highly crystalline CZTS phase after sulfurization at temperatures above 500 °C. The composition of the CZT film barely changes during the sulfurization, and a small amount of CuS-based secondary phases exists even at 550 °C. However, a quick post-annealing KCN treatment effectively and selectively removes the secondary phase, evidenced by the Raman spectroscopy and elemental.

The open-circuit voltage of bulk heterojunction polymer solar cells utilizing 1,8-diiodooctane (DIO) as a processing additive was greatly improved by using an organic layer coated TiO 2 nanoparticle interfacial layer inserted between the active layer and the Al electrode. The transient photovoltage measurement revealed that there was significant non-geminate recombination at the DIO-processed active layer/Al electrode interface. Reduced open-circuit voltage ( V OC ) of the photovoltaic devices and high water contact angle of the DIO-processed active layer showed that the DIO-processed active layer has an undesirable surface composition for the electron collection. The organic layer coated TiO 2 nanoparticle interfacial layer effectively prevented the non-geminate recombination at the active layer/Al interface. As a result, we were able to significantly improve the V OC and power conversion efficiency from 0.46 V and 2.13% to 0.62 V and 3.95%, respectively.

We report a promising approach to fabricate organic–inorganic hybrid tandem photovoltaic devices with a reversed configuration. High bandgap hydrogenated amorphous silicon (a-Si:H) was deposited with plasma-enhanced chemical vapor deposition onto a solution-processed low bandgap organic photovoltaic (OPV) subcell. Two important factors for efficient tandem solar cells, interfacial series resistance (RS,int) and balanced photocurrents, were investigated. The intimate interfacial contact eliminated the RS,int, and sufficient transmittance of the OPV front subcell led to the well-balanced photocurrents. As a result, this reversed hybrid tandem device showed an enhanced efficiency of 3.3% and an open-circuit voltage of 1.51 V.

A low-cost, nonvacuum fabrication route for CuInSe2 and CuInS2 thin films is presented. To produce these films, binder-free colloidal precursors were prepared using Cu–In intermetallic nanoparticles that were synthesized via a chemical reduction method. The Cu–In alloy precursor films were transformed to CuInSe2 and CuInS2 by reactive annealing in chalcogen-containing atmospheres at atmospheric pressure. The as-synthesized nanoparticles and the annealed films were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray spectrometry, electron probe X-ray microanalysis, Raman spectroscopy, and Auger electron spectroscopy depth profile measurements to elucidate the phase evolution pathway and the densification mechanism of the Cu–In–Se–S system. Solar cell devices made with CuInSe2 and CuInS2 absorbing layers exhibited power conversion efficiencies of 3.92% and 2.28%, respectively. A comparison of the devices suggested that the microstructur...

We characterized the electrical properties of ambipolar polymer field-effect transistors (PFETs) based on the low-band-gap polymer, pNAPDO-DPP-EH. The polymer consisted of electron-rich 2,6-di(thienyl)naphthalene units with decyloxy chains (NAPDO) and electron-deficient diketopyrrolopyrrole units with 2-ethylhexyl chains (DPP-EH). The as-spun pNAPDO-DPP-EH PFET device exhibited ambipolar transport properties with a hole mobility of 3.64 × 10–3 cm2/(V s) and an electron mobility of 0.37 × 10–3 cm2/(V s). Thermal annealing of the polymer film resulted in a dramatic increase in the carrier mobility. Annealing at 200 °C yielded hole and electron mobilities of 0.078 and 0.002 cm2/(V s), respectively. The mechanism by which the mobility had improved was investigated via grazing incidence X-ray diffraction studies, atomic force microscopy, and temperature-dependent transport measurements. These results indicated that thermal annealing improved the polymer film crystallinity and promoted the formation of a longer...

A facile method for increasing the reaction rate of dye adsorption, which is the most time-consuming step in the production of dye-sensitized solar cells (DSSCs), was developed. Treatment of a TiO2 photoanode with aqueous nitric acid solution (pH 1) remarkably reduced the reaction time required to anchor a carboxylate anion of the dye onto the TiO2 nanoparticle surface. After optimization of the reaction conditions, the dye adsorption process became 18 times faster than that of the conventional adsorption method. We studied the influence of the nitric acid treatment on the properties of TiO2 nanostructures, binding modes of the dye, and adsorption kinetics, and found that the reaction rate improved via the synergistic effects of the following: (1) electrostatic attraction between the positively charged TiO2 surface and ruthenium anion increases the collision frequency between the adsorbent and the anchoring group of the dye; (2) the weak anchoring affinity of NO3(-) in nitric acid with metal oxides enables the rapid coordination of an anionic dye with the metal oxide; and (3) sufficient acidity of the nitric acid solution effectively increases the positive charge density on the TiO2 surface without degrading or transforming the TiO2 nanostructure. These results demonstrate the developed method is effective for reducing the overall fabrication time without sacrificing the performance and long-term stability of DSSCs.

We report the synthesis, characterization, and solar cell properties of new donor–acceptor-type low band gap polymers (POBDTPD and PEBDTPD) that incorporate dialkoxybenzodithiophene (BDT) as the donor and N-octyl-2,7-dithia-5-azacyclopenta[a]pentalene-4,6-dione (DTPD) as the acceptor. The newly developed DTPD moiety was carefully designed to lower a band gap via strong interaction between donor–acceptor moieties and keep polymer energy levels deep. Remarkably, the DTPD acceptor moiety effectively widens the light absorption range of the polymers up to ∼900 nm while positioning their HOMO and LUMO levels in the optimal range, i.e., −5.3 and −4.0 eV, respectively, for high power conversion efficiencies (PCEs) as we intended. Solar cell devices were fabricated according to the structure ITO/PEDOT:PSS/photoactive (polymer:PC70BM)/TiO2/Al. The POBDTPD devices exhibited a PCE of 4.7% with a Voc of 0.70 V, a Jsc of 10.6 mA/cm2, and a FF of 0.64. The PEBDTPD devices yielded a higher PCE of 5.3% with a Voc of 0.72...

For the practical application of dye-sensitized solar cells (DSSCs), it is important to replace the conventional organic solvents based electrolyte with environmentally friendly and stable ones, due to the toxicity and leakage problems. Here we report a noble water-based thixotropic polymer gel electrolyte containing xanthan gum, which satisfies both the environmentally friendliness and stability against leakage and water intrusion. For application in DSSCs, it was possible to infiltrate the prepared electrolyte into the mesoporous TiO2 electrode at the fluidic state, resulting in sufficient penetration. As a result, this electrolyte exhibited similar conversion efficiency (4.78% at 100 mW cm(-2)) and an enhanced long-term stability compared to a water-based liquid electrolyte. The effects of water on the photovoltaic properties were examined elaborately from the cyclic voltammetry curves and impedance spectra. Despite the positive shift in the conduction band potential of the TiO2 electrode, the open-circuit voltage was enhanced by addition of water in the electrolyte due to the greater positive shift in the I(-)/I3(-) redox potential. However, due to the dye desorption and decreased diffusion coefficient caused by the water content, the short-circuit photocurrent density was reduced. These results will provide great insight into the development of efficient and stable water-based electrolytes.

The effect of the heating rate during the sulfurization process on the properties of Cu2ZnSnS4 (CZTS) thin film solar cells was investigated. A moderate heating rate of ~10 oC/min was found to result in a modest solar cell performance (2 %), whereas the higher heating rates resulted in worse performances. In the CZTS thin films annealed with the highest heating rate, the segregation of Cu atoms towards the outer surface of the films, which is believed to lead to shunting of the solar cells.

Thin light-active layers of the CuInSe2 solar cell were prepared on Mo-coated sodalime glass substrates by one-step electrodeposition and post-annealing. The structure, morphology, and composition of CuInSe2 film could be controlled by deposition parameters, such as the composition of metallic precursors, the concentration of complexing agents, and the temperature of post-annealing with elemental selenium. A dense and uniform Cu-poor CuInSe2 film was successfully obtained in a range of parametric variation of electrodeposition with a constant voltage of -0.5 V vs. a Ag/AgCl reference electrode. The post-annealing of the film at high temperature above 500℃ induced crystallization of CuInSe2 with well-developed grains. The KCN-treatment of the annealed CuInSe2 films further induced Cu-poor CuInSe2 films without secondary phases, such as Cu2Se. The structure, morphology, and composition of CuInSe2 films were compared with respect to the conditions of electrodeposition and post-annealing using SEM, XRD, Raman, AES and EDS analysis. And the conditions for preparing device-quality CuInSe2 films by electrodeposition were proposed.

We designed and synthesized a new low band gap donor–acceptor copolymer (PDTDPP-Oct) composed of alternating dithieno[3,2- b :2′,3′- d ]thiophene and bis-thienyl-diketopyrrolo[3,4- c ]pyrrole units. The polymer films showed a very broad absorption band that extended up to 950 nm. Thermogravimetric analysis revealed good thermal stability and a high glass transition temperature of 128 °C. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the polymer were estimated to be −5.01 and −3.70 eV, respectively. Bulk heterojunction polymer solar cells were fabricated with the structure: ITO/PEDOT:PSS/polymer:PCBM/Al. The introduction of 1,8-octanedithiol as a processing additive to the polymer/PCBM blend solution significantly improved the device performance relative to devices prepared from the blend solution without the additive. This cell gave a short circuit current of −1.8 mA/cm 2 , an open circuit voltage of 0.60 V, and a fill factor of 0.52, yielding a power conversion efficiency of 0.55%. The performance improvements were mainly attributed to the fine morphology of the blend film.

Chalcopyrite CIS or CIGS have been regarded as promising absorbing materials for thin-film solar cells with widespread commercialization prospects. The most critical material properties of a CIS absorption layer that affect the overall PV performance include its microstructure and composition at a given bandgap energy. In this study, dense CISe films with high crystallinity and uniform, flat surfaces were fabricated on In2Se3/ITO employing single bath electrochemical deposition by adjusting the deposition parameters, such as the precursor concentration, pH, and applied potential. A simple formula is presented based on Faraday's law to quantitatively estimate the density of the electrodeposited thin films; from this, it was found that the as-deposited films had a very high relative density of 0.73. The high green density of the as-deposited film led to the full densification of the CISe film with ca. 10 μm sized grains. The binary selenide phase remaining in the sintered film was subsequently etched out using a KCN solution, resulting in an overall Cu-deficient composition in the film of [Cu]/[In] = 0.95.

We report high-performance of ambipolar organic field-effect transistors (FETs) based on the low band gap copolymers of pDPPT2NAP-HD and pDPPT2NAP-OD. The polymers are composed of electron-rich 2,6-di(thienyl)naphthalene (T2NAP) and electron-deficient diketopyrrolopyrrole (DPP) units with branched alkyl chains of 2-hexyldecyl (HD) or 2-octyldodecyl (OD). The polymers were polymerized via Suzuki coupling, yielding optical band gaps of ∼1.4 eV. In the transistor performance test, we observed good ambipolar transport behavior in both polymer films, and pDPPT2NAP-OD displayed hole and electron mobilities 1 order of magnitude higher than the corresponding properties of pDPPT2NAP-HD. Thermal annealing of the polymer films increased the carrier mobilities. Annealing at 150 °C provided optimal conditions yielding saturated film crystallinity and maximized carrier mobility. The highest hole and electron mobilities achieved in these polymers were 1.3 and 0.1 cm2/(V s), respectively, obtained from pDPPT2NAP-OD. The ...

The photovoltaic performance of dye-sensitized solar cells (DSSCs) employing SnO2 electrodes was investigated while increasing the content of 4-tert-butylpyridine (TBP) in the conventional liquid-type electrolyte. As the added TBP content increased, the open circuit voltage (Voc) and conversion efficiency were highly enhanced while the short circuit current (Jsc) was not much affected. With the electrolyte of 2.0 M TBP, the Voc and conversion efficiency were increased by 26 and 33%, respectively, compared with the conventional electrolyte (0.5 M TBP). The electrochemical impedance spectra revealed that the enhancement of Voc resulted from the negative shift of the SnO2 conduction band potential and the increase in resistance of electron recombination by 1 order of magnitude. It is noteworthy that the optimized concentration of TBP for the SnO2 electrode is greatly larger than that for the TiO2 electrode. This may be due to the much faster electron recombination rate and more positive conduction band poten...

Highlights: ► This work enhanced power conversion efficiency of the hybrid tandem solar cell from 1.0% to 2.6%. ► The interfacial series resistance of the tandem solar cell was eliminated by inserting ITO layer. ► This work shows the feasibility of the highly efficient hybrid tandem solar cells. -- Abstract: We demonstrate hybrid tandem photovoltaic devices with a transparent conductive interconnecting recombination layer. The series-connected hybrid tandem photovoltaic devices were developed by combining hydrogenated amorphous silicon (a-Si:H) and polymer-based organic photovoltaics (OPVs). In order to enhance the interfacial connection between the subcells, we employed highly transparent and conductive indium tin oxide (ITO) thin layer. By using the ITO interconnecting layer, the power conversion efficiency of the hybrid tandem solar cell was enhanced from 1.0% (V{sub OC} = 1.041 V, J{sub SC} = 2.97 mA/cm{sup 2}, FF = 32.3%) to 2.6% (V{sub OC} = 1.336 V, J{sub SC} = 4.65 mA/cm{sup 2}, FF = 41.98%) due to the eliminated interfacial series resistance.

Two low band gap copolymers (PQTDPP and PQTVTDPP) having quaterthiophene (QT) or bithiophene-vinylene-bithiophene (QTVT) as donor unit and diketopyrrolopyrrole (DPP) as acceptor unit have been synthesized via Stille cross-coupling polymerization. The polymers showed high thermal stability and broad light absorption with optical band gaps around 1.3 eV. Cyclic voltammetry measurements revealed that the HOMO and LUMO energy levels of QT and DPP copolymer (PQTDPP) were found to be −5.19 and −3.64 eV, respectively and those of PQTVTDPP −5.05 and −3.66 eV, respectively. X-ray diffraction patterns showed highly crystalline phase in the PQTDPP film and nearly amorphous in the PQTVTDPP film. This dramatic difference in crystallinity was attributed to the structural isomerization around vinyl groups in the PQTVTDPP polymer. Field-effect transistor measurement revealed that the PQTDPP showed high hole mobility of 0.06 cm 2 /Vs and on/off ratio of 10 6 while the PQTVTDPP showed hole mobility of 3.57×10 −4 cm 2 /Vs and on/off ratio of 10 5 , which is consistent with X-ray diffraction results. Photovoltaic devices were also fabricated using polymer:PCBM blends in the structure of ITO/PEDOT:PSS/blend/Al. The PQTDPP devices exhibited an open circuit voltage ( V oc ) of 0.58 V, a short circuit current ( J sc ) of 7.16 mA/cm 2 , a fill factor ( FF ) of 0.55 and a power conversion efficiency ( PCE ) of 2.28%, and the PQTVTDPP devices exhibited an V oc of 0.50 V, a J sc of 7.60 mA/cm 2 , a FF of 0.51 and a PCE of 1.97% under AM 1.5 illumination.

The combination of a photovoltaic (PV) and an electrolytic cell into one single system, a monolithic PV-electrolytic cell, has been suggested as an efficient solar hydrogen generation system. In this study, we demonstrate an efficient prototype electrolysis system applied to a monolithic PV-electrolytic cell. Specifically, the relatively large unit cell (active area of 36 cm2) used in the study made it possible to directly measure in volume the amount of hydrogen and oxygen generated. To enhance the activity of the electrodes we introduced channels, Co3O4 film, and Pt particles on stainless steel (SUS) substrates. The highest hydrogen production rate was obtained in the system in which Co3O4 electrocatalytic film on a SUS foil and Pt particles on a SUS plate with channels were used as an anode and a cathode, respectively.

Highly efficient cathodes for dye-sensitized solar cells (DSSCs) were developed using thin films of graphene nanosheets (GNS), which were fabricated by the electrospray method (e-spray) using aqueous dispersions of chemically driven GNS. The e-sprayed GNS films had the appropriate properties to be an efficient counter electrode (CE) for DSSCs; sufficient electrocatalytic activity for I(-)/I3(-) redox couples and low charge transfer resistance (RCT) at the CE/electrolyte interface as characterized by cyclic voltammetry and electrochemical impedance analysis. The performance of the GNS film based CEs was optimized by manipulating the density of surface chemical functional groups and plane conjugation of GNS via post thermal annealing (TA). Upon TA, the oxygen-containing surface functional groups, which have been shown to improve electrocatalytic activity of carbon based materials, were significantly reduced, while the electrical conductivity was enhanced by ∼40 times. The improvement of electrocatalytic activity and fill factor (FF) with reduced RCT of DSSCs after TA was primarily attributed to the increased charge transport within the GNS films, while the chemically prepared GNS typically contained sufficient defects, edges and surface functional groups for electrocatalysis. The performance of the DSSCs using our GNS-CEs was nearly identical (95%) to the DSSCs using the state-of-the-art CE, thermolytically prepared Pt crystals. Our e-sprayed GNS-CE based DSSCs had a higher FF (69.7%) and cell efficiency (6.93%) when compared previously reported graphene based CEs for DSSCs, demonstrating the outstanding properties of graphene as the electrodes in electrochemical devices.

Tungsten oxide layer is formed uniformly by a sol–gel technique on top of indium tin oxide as a neutral and photo-stable hole extraction layer (HEL). The solution processed tungsten oxide layer (sWO3) is fully characterized by UV–Vis, XPS, UPS, XRD, AFM, and TEM. Optical transmission of ITO/sWO3 substrates is nearly identical to ITOs. In addition, the sWO3 layer induces nearly ohmic contact to P3HT as PEDOT:PSS layer does, which is determined by UPS measurement. In case that an optimized thickness (∼10 nm) of the sWO3 layer is incorporated in the organic photovoltaic devices (OPVs) with a structure of ITO/sWO3/P3HT:PCBM/Al, the power conversion efficiency (PCE) is 3.4%, comparable to that of devices utilizing PEDOT:PSS as HEL. Furthermore, the stability of OPV utilizing sWO3 is significantly enhanced due to the air- and photo-stability of the sWO3 layer itself. PCEs are decreased to 40% and 0% of initial values, when PEDOT:PSS layers are exposed to air and light for 192 h, respectively. In contrast, PCEs are maintained to 90% and 87% of initial PCEs respectively, when sWO3 layers are exposed to the same conditions. Conclusively, we find that solution processed tungsten oxide layers can be prepared easily, act as an efficient hole extraction layer, and afford a much higher stability than PEDOT:PSS layers.

As an electrocatalyst in a monolithic PV-electrolytic cell for water splitting hydrogen generation Co3O4 films were prepared by a paste coating method using Co3O4 particles. Different sized Co3O4 particles with average diameters of 145.9, 63.3 and 36.5 nm were prepared using a supercritical hydrothermal synthesis method. Electrochemical properties with respect to the particle size in the film were investigated by evaluating overpotential, charge transfer resistance (Rct), and number of active sites (q∗). The relation between overpotential in water oxidation at 5 mA/cm2 and BET surface area showed a slope of −73.8 ± 6.6, implying strong particle size dependence on electrocatalytic activity. Moreover, the Rct and q∗ values and the actual hydrogen evolution rate indicated that the electrocatalytic activity of Co3O4 is attributed to physical properties (e.g. particle size) of the film. Whereas, intrinsic single site activity of the film was not significantly changed with respect to the particle size in the film.

In this review, we have investigated the effect of TiO 2 -based blocking layers (t-BLs), deposited ona transparent conductive oxide (TCO)-coated glass substrate, on the photovoltaic performance ofdye-sensitized solar cells (DSSCs). The t-BL was deposited using spin-coating or sputteringtechnique, and its thicknesses were varied to study the influence of the thin TiO 2 layer in betweentransparent conducting glass and nanocrystalline TiO 2 (nc-TiO 2 ). The DSSC with the t-BL showedthe improved adhesion and the suppressed charge recombination at a TCO glass substrate thanthose without the t-BL, which led to the higher conversion efficiency. Keywords: Dye-sensitized solar cell, Blocking layers, Transparent conducting oxides, Chargerecombination, Adhesion properties Received May 27, 2011 : Accepted June 3, 2011 1. Introduction Dye-sensitized solar cells have been extensivelystudied since their discovery in 1991 by Gratzel’s researchgroup 1) because they have been considered as a goodalternative to conventional silicon photovoltaic cells dueto their low production costs and colorful characteristics.As a consequence of this special attention, DSSCs withenergy conversion efficiencies higher than 11% have beenobtained using nc-TiO

In a monolithic photovoltaic-electrolysis system, photovoltaic and catalytic layers are generally constructed on both sides of a conducting substrate. For the realization of this architecture it is critical to fabricate the catalytic layer at sufficiently low temperature in order not to deteriorate the photovoltaic photoanode that is already installed on the reverse side of the catalytic layer. In this study we demonstrate successful fabrication of Co3O4 electrocatalyst films at low temperature (∼50°C) on a stainless steel substrate by a paste coating method using Nafion as a binder. The Co3O4 films were found to be catalytically efficient and stable in water splitting reaction in an alkaline aqueous solution. More importantly, the Co3O4 films casted at low temperature (∼50°C) revealed the highest hydrogen production rate in the electrolytic cell compared to the films prepared at higher temperatures (e.g. 150 and 300°C), which would be very beneficial in the construction of a monolithic photovoltaic-electrolysis system.

We demonstrate that vertically aligned carbon nanotubes can be synthesized directly on tantalum substrate via waterassisted chemical vapor deposition and evaluate their properties as electrochemical capacitors. The mean diameter of the carbon nanotubes was 7.1 ± 1.5 nm, and 70% of them had double walls. The intensity ratio of G-band to D-band in Raman spectra was as high as 5, indicating good quality of the carbon nanotubes. Owing to the alignment and low equivalent series resistance, the carbon nanotube based supercapacitors showed good rate performance. Rectangular shape of cyclic voltammogram was maintained even at the scan rate of > 1 V/s in 1 M sulfuric acid aqueous solution. Specific capacitance was well-retained (~94%) even when the discharging current density dramatically increased up to 145 A/g. Consequently, specific power as high as 60 kW/kg was obtained from as-grown carbon nanotubes in aqueous solution. Maximum specific energy of ~20 Wh/kg was obtained when carbon nanotubes were electrochemically oxidized and operated in organic solution. Demonstration of direct synthesis of carbon nanotubes on tantalum current collectors and their applications as supercapacitors could be an invaluable basis for fabrication of high performance carbon nanotube supercapacitors.