Photo-Rechargeable Asymmetric Supercapacitors Exceeding Light-to-Charge Storage Efficiency over 21% under Indoor Light.

Photo-rechargeable energy storage devices are appealing for substantial research attention because of their possible applications in the Internet of Things (IoT) and low-powered miniaturized portable electronics. However, due to the incompatibility of the photovoltaics and energy storage systems (ESSs), the overall light-to-storage efficiency is limited under indoor light conditions. Herein, a porous carbon scaffold MnO-Mn3 O4 /C microsphere-based monolithic dye-sensitized photo-rechargeable asymmetric supercapacitor (DSPC) is fabricated. The integrated DSPC has a high areal specific capacitance of 281.9 mF cm-2 at the discharge rate of 0.01 mA cm-2 . The light-to-electrical conversion efficiency of the DSSC is 27.6% under the 1000 lux compact fluorescent lamp (CFL). The DSPC shows an outstanding light-to-charge storage efficiency of 21.6%, which is higher than that reported ever. Furthermore, the fabricated polymer gel electrolyte-based quasi-solid state (QSS) DSPC shows similar overall conversion efficiency with superior cycling capability. This work shows a convenient fabrication process for a wireless power pack of interest with outstanding performance.

Organic Dyes with Well-Defined Structures for Highly Efficient Dye-Sensitised Solar Cells Based on a Cobalt Electrolyte.

Seven SGT organics dyes, containing bis-dimethylfluoreneyl amino groups with a dialkoxyphenyl unit as an electron donor and a cyanoacrylic acid group as an anchoring group, connected with oligothiophenes, fused thiophenes and benzothiadiazoles as π-bridges, were designed and synthesised for applications in dye-sensitised solar cells (DSSCs). The photovoltaic performance of DSSCs based on organic dyes with oligothiophenes depends on the molecular structure of the dyes, in terms of the length change of the π-bridging units. The best performance was found with a π-bridge length of about 6 Å. To further enhance the photovoltaic performance associated with this concept, cyclopenta[1,2-b:5,4-b']dithiophene (CPDT) and benzothiadiazole were introduced into the π-bridge unit. As a result, the DSSC based on the organic dye containing the CPDT moiety showed the best photovoltaic performance with a short-circuit photocurrent density (Jsc ) of 14.1 mA cm(-2) , an open-circuit voltage (Voc ) of 0.84 V and a fill factor (FF) of 0.72, corresponding to an overall conversion efficiency (η) of 8.61 % under standard AM 1.5 irradiation.

Two Dimensional Aggregation Behaviors of Quinoxaline Dendrimers.

This study focuses on the molecular behavior of two dendrimers containing a hydrophilic core group (carboxyl group) and hydrophobic branches (quinoxaline and methoxyphenyl groups), 2,3-bis(4-(2,3- bis(4-methoxyphenyl)quinoxalin-6-yloxy)phenyl)quinoxaline-6-carb-oxylic acid (G2) and 2,3-bis(4-(2,3-bis(4-(2,3-bis(4-methoxyphenyl)quinoxalin-6-yloxy)phe-nyl)quinoxalin-6-y-oxy)phenyl) quin oxaline-6-carboxylic acid (G3) at the air-water interface. To understand the mechanism of the self-assembly of these molecules, we measured the surface pressure-area (III-A) isotherm and investigated the surface morphology of Langmuir-Blodgett films transferred onto hydrophilic silicon wafers using atomic force microscopy (AFM). Upon compression, G2 molecules stand up and steadily make close-packed monolayer whereas G3 molecules form circular domains and gradually make aggregates of domains. These results were confirmed by the X-ray Reflectivity (XRR) profiles of G2 and G3 monolayers transferred onto silicon substrates.

A Eu(III) tetrakis(ß-diketonate) dimeric complex: photophysical properties, structural elucidation by Sparkle/AM1 calculations, and doping into PMMA films and nanowires.

Reaction of Ln(III) with a tetrakis(diketone) ligand H4L [1,1'-(4,4'-(2,2-bis((4-(4,4,4-trifluoro-3-oxobutanoyl) phenoxy)methyl)propane-1,3-diyl)bis(oxy)bis(4,1-phenylene))bis(4,4,4-trifluorobutane-1,3-dione)] gives new podates which, according to mass spectral data and Sparkle/AM1 calculations, can be described as dimers, (NBu4[LnL])2 (Ln = Eu, Tb, Gd:Eu), in both solid-state and dimethylformamide (DMF) solution. The photophysical properties of the Eu(III) podate are compared with those of the mononuclear diketonate (NBu4[Eu(BTFA)4], BTFA = benzoyltrifluoroacetonate), the crystal structure of which is also reported. The new Eu(III) dimeric complex displays bright red luminescence upon irradiation at the ligand-centered band in the range of 250-400 nm, irrespective of the medium. The emission quantum yields and the luminescence lifetimes of (NBu4[EuL])2 (solid state: 51% ± 8% and 710 ± 2 µs; DMF: 31% ± 5% and 717 ± 1 µs) at room temperature are comparable to those obtained for NBu4[Eu(BTFA)4] (solid state: 60 ± 9% and 730 ± 5 µs; DMF: 30 ± 5% and 636 ± 1 µs). Sparkle/AM1 calculations were utilized for predicting the ground-state geometries of the Eu(III) dimer. Theoretical Judd-Ofelt and photoluminescence parameters, including quantum yields, predicted from this model are in good agreement with the experimental values, proving the efficiency of this theoretical approach implemented in the LUMPAC software (http://lumpac.pro.br). The kinetic scheme for modeling energy transfer processes show that the main donor state is the ligand triplet state and that energy transfer occurs on both the (5)D1 (44.2%) and (5)D0 (55.8%) levels. Furthermore, the newly obtained Eu(III) complex was doped into a PMMA matrix to form highly luminescent films and one-dimensional nanowires having emission quantum yield as high as 67%-69% (doping concentration = 4% by weight); these materials display bright red luminescence even under sunlight, so that interesting photonic applications can be foreseen.

Tailor-made hole-conducting coadsorbents for highly efficient organic dye-sensitized solar cells.

The Y-shaped, low molecular mass, hole-conductor (HC), acidic coadsorbents 4-{3,7-bis[4-(2-ethylhexyloxy)phenyl]-10H-phenothiazin-10-yl}benzoic acid (PTZ1) and 4-{3,7-bis[4-(2-ethylhexyloxy)phenyl]-10H-phenothiazin-10-yl}biphenyl-4-carboxylic acid (PTZ2) were developed. Owing to their tuned and negative-shifted HOMO levels (vs. NHE), they were used as HC coadsorbents in dye-sensitized solar cells (DSSCs) to improve cell performance through desired cascade-type hole-transfer processes. Their detailed functions as HC coadsorbents in DSSCs were investigated to obtain evidence for the desired cascade-type hole-transfer processes. They have multiple functions, such as preventing π-π stacking of dye molecules, harvesting light of shorter wavelengths, and faster dye regeneration. By using PTZ2 as the tailor-made HC coadsorbent on the TiO2 surface with the organic dye NKX2677, an extremely high conversion efficiency of 8.95 % was achieved under 100 mW cm(-2) AM 1.5G simulated light (short-circuit current JSC =16.56 mA cm(-2) , open-circuit voltage VOC =740 mV, and fill factor of 73 %). Moreover, JSC was increased by 13 %, VOC by 27 % and power-conversion efficiency by 49 % in comparison to an NKX2677-based DSSC without an HC coadsorbent. This is due to the HC coadsorbent having a HOMO energy level well matched to that of the NKX-2677 dye to induce the desired cascade-type hole-transfer processes, which are associated with a slower charge recombination, fast dye regeneration, effective screening of liquid electrolytes, and an induced negative shift of the quasi-Fermi level of the electrode. Thus, this new class of Y-shaped, low molecular weight, organic, HC coadsorbents based on phenothiazine carboxylic acid derivatives hold promise for highly efficient organic DSSCs.

Redox Shuttle-Based Electrolytes for Dye-Sensitized Solar Cells: Comprehensive Guidance, Recent Progress, and Future Perspective.

A redox electrolyte is a crucial part of dye-sensitized solar cells (DSSCs), which plays a significant role in the photovoltage and photocurrent of the DSSCs through efficient dye regeneration and minimization of charge recombination. An I-/I3 - redox shuttle has been mostly utilized, but it limits the open-circuit voltage (V oc) to 0.7-0.8 V. To improve the V oc value, an alternative redox shuttle with more positive redox potential is required. Thus, by utilizing cobalt complexes with polypyridyl ligands, a significant power conversion efficiency (PCE) of above 14% with a high V oc of up to 1 V under 1-sun illumination was achieved. Recently, the V oc of a DSSC has exceeded 1 V with a PCE of around 15% by using Cu-complex-based redox shuttles. The PCE of over 34% in DSSCs under ambient light by using these Cu-complex-based redox shuttles also proves the potential for the commercialization of DSSCs in indoor applications. However, most of the developed highly efficient porphyrin and organic dyes cannot be used for the Cu-complex-based redox shuttles due to their higher positive redox potentials. Therefore, the replacement of suitable ligands in Cu complexes or an alternative redox shuttle with a redox potential of 0.45-0.65 V has been required to utilize the highly efficient porphyrin and organic dyes. As a consequence, for the first time, the proposed strategy for a PCE enhancement of over 16% in DSSCs with a suitable redox shuttle is made by finding a superior counter electrode to enhance the fill factor and a suitable near-infrared (NIR)-absorbing dye for cosensitization with the existing dyes to further broaden the light absorption and enhance the short-circuit current density (J sc) value. This review comprehensively analyzes the redox shuttles and redox-shuttle-based liquid electrolytes for DSSCs and gives recent progress and perspectives.

D-π-A Structured Porphyrin and Organic Dyes with Easily Synthesizable Donor Units for Low-Cost and Efficient Dye-Sensitized Solar Cells.

This study aimed to develop low-cost D-π-A structured porphyrin and organic dyes with easily synthesizable donor units instead of the conventional complex multistep synthetic donor unit of Hexyloxy-BPFA [bis(7-(2,4-bis(hexyloxy)phenyl)-9,9-dimethyl-9H-fluoren-2-yl)amine] used in SGT-021 and SGT-149 as well-known record cosensitizers with an extremely high power conversion efficiency (PCE). The design strategy concerned the easier synthesis of low-cost donor units with inversion structures in donor groups via donor structural engineering, particularly by changing the position of the fluorene and phenylene units in the donor moiety while keeping the π-bridge and acceptor unit unchanged, leading to the synthesis of two D-π-A structured porphyrins [SGT-021(D0) and SGT-021(D)] and one D-π-A structured organic sensitizer [SGT-149(D)] for dye-sensitized solar cells (DSSCs). Specifically, porphyrin SGT-021(D0) incorporated two hexyl chains into the 9-position of each fluorene, while SGT-021(D) and SGT-149(D) substituted two hexyloxy chain units to the terminal position of each fluorene in the donor groups of porphyrin dyes. The effect of the position of the fluorene and phenylene units in the donor moiety on the photochemical and electrochemical properties, as well as the photovoltaic performance, was compared with the reference dyes of SGT-021 and SGT-149, previously reported by the research group. After optimizing the DSSC devices, SGT-021(D) and SGT-021(D0) achieved a high PCE of 11.6 and 10.5%, respectively, while SGT-149(D) exhibited a little lower PCE of 10.3% under the standard AM 1.5G light intensity. The cell performance of DSSC devices based on SGT-021(D) and SGT-149(D) was inferior to the corresponding reference dyes of SGT-021 and SGT-149 due to their lower donating ability of Hexyloxy-BPFA than Hexyloxy-BFPA.

Synergistic Effect of Size-Tailored Structural Engineering and Postinterface Modification for Highly Efficient and Stable Dye-Sensitized Solar Cells.

Despite significant progress in device performance, dye-sensitized solar cells (DSSCs) continue to fall short of their theoretical potential. Moreover, research in recent years needs to pay more attention to improving the device fabrication process. To achieve the theoretical efficiency limit, it is crucial to optimize the interface between the dye and TiO2 nanoparticles in the entire device stack. Our study indicates that optimizing the structure or size of the coadsorbents and implementing a monolayer adsorption process can be an effective strategy to reduce charge recombination and enhance light-harvesting properties. Our research aims to develop a surface-coating adsorbent plan that controls the TiO2 nanoparticle interface to achieve the radiative limit of power conversion efficiency (PCE). Specifically, we utilized 2-thiophenecarboxylic acid (THCA) or chenodeoxycholic acid (CDCA) as postinterfacial surface-coating adsorbents. Our results demonstrate that this approach effectively achieves the desired PCE limit. Combined with the coadsorbent structure engineering and interface optimization, the device increased the packing area on the TiO2 nanoparticles' surface, reaching an improved PCE of over 13.17% under simulated sunlight (1.5G), which is the highest efficiency of a porphyrin single dye-based DSSC. In particular, this practical approach was also applied to a large-area DSSC with an area of 3 cm2, yielding a remarkable PCE of 9.04%. Furthermore, when applied to a polymer gel electrolyte, this novel approach recorded the highest PCE of 11.16% with a long-term operational stability of up to 1000 h for the quasi-solid-state DSSCs. Our research findings provide a promising avenue for achieving high-performance DSSCs with ease of access and demonstrate practical applications as alternatives to conventional power sources.

Influence of the π-Bridge-Fused Ring and Acceptor Unit Extension in D-π-A-Structured Organic Dyes for Highly Efficient Dye-Sensitized Solar Cells.

Three new D-π-A-structured organic dyes, coded as SGT-138, SGT-150, and SGT-151, with the expansion of π-conjugation in the π-bridge and acceptor parts have been developed to adjust HOMO/LUMO levels and to expand the light absorption range of organic dyes. Referring to the SGT-137 dye, the π-bridge group was extended from the 4-hexyl-4H-thieno[3,2-b]indole (TI) to the 9-hexyl-9H-thieno[2',3':4,5]thieno[3,2-b]indole (TII), and the acceptor group was extended from (E)-3-(4-(benzo[c][1,2,5]thiadiazol-4-yl)phenyl)-2-cyanoacrylic acid (BTCA) to (E)-3-(4-(benzo[c][1,2,5]thiadiazol-4-ylethynyl)phenyl)-2-cyanoacrylic acid (BTECA), where TII was introduced as a π-bridging unit for the first time. It was determined that both extensions are promising strategies to enhance the light-harvesting ability. They present several features, such as (i) efficiently intensifying the extinction coefficient and expanding the absorption bands; (ii) exhibiting enhanced intramolecular charge transfer in comparison with the SGT-137; and (iii) being favorable to photoelectric current generation of dye-sensitized solar cells (DSSCs) with cobalt electrolytes. In particular, the π-spacer extension from TI to TII was useful for modulating the HOMO energy levels, while the acceptor extension from BTCA to BTECA was useful for modulating the LUMO energy levels. These phenomena could be explained with the aid of density functional theory calculations. Finally, the DSSCs based on new SGT-dyes with an HC-A1 co-adsorbent presented good power conversion efficiencies as high as 11.23, 11.30, 11.05, and 10.80% for SGT-137, SGT-138, SGT-150, and SGT-151, respectively. Furthermore, it was determined that the use of the bulky co-adsorbent, HC-A1, can effectively suppress the structural relaxation of dyes in the excited state, thereby enhancing the charge injection rate of SGT-dyes. The observations in time-resolved photoluminescence were indeed consistent with the variation in the PCE, quantitatively.

Metal ion coordination with an asymmetric fan-shaped dendrimer at the air-water interface.

Metal coordination to monolayers of 4-{10-[4-(3,5-bis-benzyloxy)-phenyl]-anthracen-9-yl}-benzoic acid ([G1-An]-CO(2)H, G1) and 4-(10-{4-[3,5-bis-(3,5-bis-benzyloxy)-benzyloxy]-phenyl}-anthracen-9-yl)-benzoic acid ([G2-An]-CO(2)H, G2) at the air-water interface and to Langmuir-Blodgett (LB) films was investigated using surface pressure-area isotherms, ultraviolet-visible (UV-vis) spectroscopy, atomic force microscopy (AFM), and X-ray reflectivity (XRR). Surface pressure-area isotherms show that G1 and G2 have different limiting areas according to the type of subphase. The limiting area of G1 and G2 increased more with Al(3+) than with Eu(3+) in the subphase. This result indicates that the hydrophilic core group is anchored to ions in the water via bidentate chelates with the carboxylate oxygen atoms of G1 and G2. Circular domains and aggregates were observed for the LB film. The different behavior of Eu(3+) and Al(3+) complexes is originated from the intrinsic nature of the ion, i.e., coordination number.

Well-dispersed Te-doped mesoporous carbons as Pt-free counter electrodes for high-performance dye-sensitized solar cells.

A tellurium-doped carbon nanomaterial (Te-MC(P)) was newly developed by the soft-templated carbonization of the PAN-b-PBA copolymer with poly(3-hexyltellurophene). Te-MC(P) was characterized with various characterization methods, including the nitrogen sorption isotherm measurement (BET), X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS), which reveal that the Te atoms are homogeneously dispersed in the three-dimensional hierarchical, graphite-like mesoporous carbon matrix with a Te doping level of 0.27 atom %. Based on the characterization results, the electrocatalytic ability of Te-MC(P) was evaluated by using a symmetrical dummy cell test with both Co(bpy)32+/3+ (bpy = 2,2'-bipyridine) and I-/I3- redox electrolytes as counter electrodes (CEs). The Te-MC(P) CEs showed remarkably lower charge-transfer resistance (Rct) values by approximately 10 times in the electrochemical impedance spectroscopy (EIS) measurement, compared to the counterpart platinum (Pt) and the tellurium-based material (Te-MC(A)), prepared with a telluric acid precursor that has a lower Te doping level of 0.15 at%. As a result, the excellent electrocatalytic ability of Te-MC(P) resulted in the improvement of photovoltaic performance. The power conversion efficiencies (PCEs) of Te-MC(P)-based dye-sensitized solar cells (DSSCs) were 12.69% for the Co(bpy)32+/3+ redox electrolyte with the SGT-021 porphyrin dye and 9.73% for the I-/I3- redox electrolyte with the N719 ruthenium dye. Furthermore, Te- MC(P) CEs exhibited remarkable electrochemical stability in the two redox electrolytes. These results could suggest that the Te-MC(P) CE is one of the best promising alternatives to Pt CEs as a low-cost, highly stable and efficient electrocatalytic CE for practical applications.

Three-dimensional tellurium and nitrogen Co-doped mesoporous carbons for high performance supercapacitors.

Tellurium-doped mesoporous carbon composite materials (Te/NMC) have been prepared by a facile intercalation method in the presence of nitrogen-doped mesoporous carbon (NMC) with tellurium powder, for the first time. The effects of the co-doped N and Te in the mesoporous carbon matrix on the physical/chemical properties and capacitance performances were investigated via the use of various characterization methods and electrochemical studies. The as-prepared NMC and Te/NMC materials were found to mainly be composed of mesopores and maintained the 3D hierarchical graphite-like structure with lots of defect sites. By intercalation of Te atoms into the NMC materials, 2.12 at% (atom%) of Te was doped into NMC and the specific surface area of Te/NMC (261.07 m2 g-1) decreased by about 1.5 times compared to that of NMC (437.96 m2 g-1). In electrochemical measurements as a supercapacitor (SC) electrode, the Te/NMC based electrode, even with its lower porosity parameters, exhibited a higher capacitive performance compared to the NMC-based electrode. These results for Te/NMC arise due to the pseudo-capacitive effect of doped Te and the increase in the capacitive area available from the formation of interconnections in the mesoporous carbons through Te-O bonds. As a result, the synergetic effect of the Te and N atoms enables Te/NMC to exhibit the highest specific capacitance of 197 F g-1 at a current density of 0.5 A g-1. Moreover, remarkable long-term cycling stability with the retention of more than 95% of the initial capacitance is observed for Te/NMC at a current density of 5 A g-1 and also for 1000 charge-discharge cycles.

Mechanism for Preserving Volatile Nitrogen Dioxide and Sustainable Redox Mediation in the Nonaqueous Lithium-Oxygen Battery.

Excessive overpotential during charging is a major hurdle in lithium-oxygen (Li-O2) battery technology. NO2-/NO2 redox mediation is an efficient way to substantially reduce the overpotential and to enhance oxygen efficiency and cycle life by suppressing parasitic reactions. Considering that nitrogen dioxide (NO2) is a gas, it is quite surprising that NO2-/NO2 redox reactions can be sustained for a long cycle life in Li-O2 batteries with such an open structure. A detailed study with in situ differential electrochemical mass spectrometry (DEMS) elucidated that NO2 could follow three reaction pathways during charging: (1) oxidation of Li2O2 to evolve oxygen, (2) vaporization, and (3) conversion into NO3-. Among the pathways, Li2O2 oxidation occurs exclusively in the presence of Li2O2, which suggests that NO2 has high reactivity to Li2O2. At the end of the charging process, most of the volatile oxidized couple (NO2) is stored by conversion to a stable third species (NO3-), which is then reused for producing the reduced couple (NO2-) in the next cycle. The dominant reaction of Li2O2 oxidation involves the temporary storage of NO2 as a stable third species during charging, which is an innovative way for preserving the volatile redox couple, resulting in a sustainable redox mediation for a high-performance Li-O2 battery.

Excited-state intramolecular proton transfer on 2-(2'-hydroxy-4'-R-phenyl)benzothiazole nanoparticles and fluorescence wavelength depending on substituent and temperature.

The fluorescence emission properties of 2-(2'-hydroxy-4'-R-phenyl)benzothiazole (HBT-R) nanoparticles with different substituents (R = -COOH, -H, -CH(3), -OH, and -OCH(3)) were investigated using spectroscopic and theoretical methods. HBT-Rs displayed dual enol and keto (excited-state intramolecular proton transfer (ESIPT)) emissions in nonpolar solvents. The spectral change of their ESIPT emissions was affected differently by the electron donating (or withdrawing) power of the substituents; a bathochromic shift for the electron donating group and a hypsochromic shift in electron withdrawing group. In addition, the changes in energy levels calculated by the ab initio method were consistent with the spectral shifts of HBT-R in solution. We prepared aggregated HBT-R nanoparticles using a simple reprecipitation process in tetrahydrofuran-water solvents. The ESIPT emission of aggregated HBT-R nanoparticles was strongly enhanced (over 45 times) compared to those of monomer HBT-Rs in toluene, as markedly shifted ESIPT emissions are observed at longer wavelength without any quenching by self-absorption. Aggregated HBT-R nanoparticles showed longer lifetimes than those of monomer molecules. The temperature effect on the aqueous dispersion of the aggregated HBT-R nanoparticles was also explored. It shows a fluorescent ratiometric change in a range of temperature from 7 to 65 degrees C. A mechanism of a temperature-dependent equilibrium between the nanoparticles and the solvated enols is proposed for the emission color change.

Recent progress on nanostructured carbon-based counter/back electrodes for high-performance dye-sensitized and perovskite solar cells.

Dye-sensitized solar cells (DSSCs) and perovskite solar cells (PSCs) favor minimal environmental impact and low processing costs, factors that have prompted intensive research and development. In both cases, rare, expensive, and less stable metals (Pt and Au) are used as counter/back electrodes; this design increases the overall fabrication cost of commercial DSSC and PSC devices. Therefore, significant attempts have been made to identify possible substitutes. Carbon-based materials seem to be a favorable candidate for DSSCs and PSCs due to their excellent catalytic ability, easy scalability, low cost, and long-term stability. However, different carbon materials, including carbon black, graphene, and carbon nanotubes, among others, have distinct properties, which have a significant role in device efficiency. Herein, we summarize the recent advancement of carbon-based materials and review their synthetic approaches, structure-function relationship, surface modification, heteroatoms/metal/metal oxide incorporation, fabrication process of counter/back electrodes, and their effects on photovoltaic efficiency, based on previous studies. Finally, we highlight the advantages, disadvantages, and design criteria of carbon materials and fabrication challenges that inspire researchers to find low cost, efficient and stable counter/back electrodes for DSSCs and PSCs.

Polymer Gel Electrolytes Based on PEG-Functionalized ABA Triblock Copolymers for Quasi-Solid-State Dye-Sensitized Solar Cells: Molecular Engineering and Key Factors.

The molecular weights and structural properties of polymers play key roles in the efficiency of gelators in polymer gel electrolytes (PGEs) for quasi-solid-state dye-sensitized solar cells (QSS-DSSCs). To find an appropriate gelator, we synthesized well-defined poly(acrylonitrile-co-N,N-dimethylacrylamide)-block-poly(ethylene glycol)-block-poly(acrylonitrile-co-N,N-dimethylacrylamide) ABA triblock copolymers with various molecular weights and copolymer compositions by reversible addition-fragmentation chain-transfer polymerization. The ratio of acrylonitrile (AN)/N,N-dimethylacrylamide (DMAA) in the triblock copolymers influences their solubility in liquid electrolytes (LEs) and thermal stability. The highest thermal stability was up to 360 °C, and this was achieved by the polymer with an AN/DMAA ratio of ≤4. The thermal stability was related to excessive randomness in the P(AN-co-DMAA) block that hinders cyclization among nitrile groups. Both the molecular weights and the AN/DMAA ratios enabled gel formation by controlling the amount of the polymer, and hence, they influence the ionic conductivity and diffusion as well. Based on the electrochemical properties, polymers with molecular weights above 100 kg/mole were efficient as PGEs in QSS-DSSCs. The overall power conversion efficiency (PCE) of 14 wt % SGT-626 PGE-based QSS-DSSCs was 9.72% under AM 1.5G solar illumination, comparable with an overall PCE of 9.79% for LE DSSCs. The overall PCE of the QSS-DSSCs further increased to 10.02% by incorporating 3 wt % TiO2 nanoparticles in the 14 wt % SGT-626 PGE. The SGT-626 PGE-based QSS-DSSC was also tested under indoor light conditions, and the best PCE of 21.26% was achieved under a white LED light of 1000 lux, which is higher than the PCE of 19.94% for the LE DSSC. The long-term device stability test under adverse conditions (50 °C and 1 sun illumination) reveals the improved stability of PGE-based QSS-DSSCs over LE DSSCs. In terms of PCE and long-term device stability, our PGE QSS-DSSCs have great potential over LE DSSCs for future indoor and outdoor applications.

In situ preparation of Ru-N-doped template-free mesoporous carbons as a transparent counter electrode for bifacial dye-sensitized solar cells.

The development of a highly active, long-lasting, and cost-effective electrocatalyst as an alternative to platinum (Pt) is a vital issue for the commercialization of dye-sensitized solar cells. In this study, Ru-N-doped template-free mesoporous carbon (Ru-N-TMC) was prepared by the direct stabilization and carbonization of the poly(butyl acrylate)-b-polyacrylonitrile (PBA-b-PAN) block copolymer and ruthenium(iii) acetylacetonate [Ru(acac)3]. During the stabilization process, microphase separation occurred in the PBA-b-PAN block copolymer due to the incompatibility between the two blocks, and the PAN block transformed to N-doped semi-graphitic carbon. In the carbonization step, the PBA block was eliminated as a porous template, creating hierarchal mesopores/micropores. Meanwhile, Ru(acac)3 was decomposed to Ru, which was homogeneously distributed over the carbon substrate and anchored through N and O heteroatoms. The resulting Ru-N-TMC showed ultra-low charge transfer resistance (Rct = 0.034 Ω cm2) in the Co(bipyridine)33+/2+ reduction reaction, indicating very high electrocatalytic ability. Even though it is a transparent counter electrode (CE, average visible transmittance of 42.25%), covering a small fraction of the fluorine doped tin oxide (FTO)/glass substrate with Ru-N-TMC, it led to lower charge transfer resistance (Rct = 0.55 Ω cm2) compared to Pt (Rct = 1.00 Ω cm2). The Ru-N-TMC counter electrode exhibited a superior power conversion efficiency (PCE) of 11.42% compared to Pt (11.16%) when employed in SGT-021/Co(bpy)33+/2+ based dye-sensitized solar cells (DSSCs). Furthermore, a remarkable PCE of 10.13% and 8.64% from front and rear illumination, respectively, was obtained when the Ru-N-TMC counter electrode was employed in a bifacial DSSC. The outstanding catalytic activity and PCE of Ru-N-TMC were due to the high surface area of Ru-N-TMC, which contained numerous active species (Ru and N), easily facilitated to redox ions through the hierarchical microporous/mesoporous structure.

The complete chloroplast genome of Douinia plicata (Lindb.) Konstant. & Vilnet (Scapaniaceae, Jungermanniales).

We completed chloroplast genome of Douinia plicata (Lindb.) Konstant. & Vilnet., presenting morphological features including denticulate leaf margin, verrucose cuticle on base of leaves, and 80-100° keel angle with stem at the midleaf. It is 118,797 bp long (GC ratio is 33.9%) and has four subregions: 81,142 bp of large single copy (31.9%) and 19,611 bp of small single copy (31.0%) regions are separated by 9,017 bp of inverted repeat (46.3%) regions including 130 genes (86 protein-coding genes, eight rRNAs, and 36 tRNAs). Phylogenetic trees show D. plicata is clustered with two Scapania species.

Dopant-Free Triazatruxene-Based Hole Transporting Materials with Three Different End-Capped Acceptor Units for Perovskite Solar Cells.

A series of dopant-free D-π-A structural hole-transporting materials (HTMs), named as SGT-460, SGT-461, and SGT-462, incorporating a planner-type triazatruxene (TAT) core, thieno[3,2-b]indole (TI) π-bridge and three different acceptors, 3-ethylthiazolidine-2,4-dione (ED), 3-(dicyano methylidene)indan-1-one (DI), and malononitrile (MN), were designed and synthesized for application in perovskite solar cells (PrSCs). The effect of three acceptor units in star-shaped D-π-A structured dopant-free HTMs on the photophysical and electrochemical properties and the photovoltaic performance were investigated compared to the reference HTM of 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (spiro-OMeTAD). Their highest occupied molecular orbital (HOMO) energy levels were positioned for efficient hole extraction from a MAPbCl3-xIx layer (5.43 eV). The hole mobility values of the HTMs without dopants were determined to be 7.59 × 10-5 cm2 V-1 s-1, 5.13 × 10-4 cm2 V-1 s-1, and 7.61 × 10-4 cm2 V-1 s-1 for SGT-460-, SGT-461-, and SGT-462-based films. The glass transition temperature of all HTMs showed higher than that of the spiro-OMeTAD. As a result, the molecular engineering of a planer donor core, π-bridge, and end-capped acceptor led to good hole mobility, yielding 11.76% efficiency from SGT-462-based PrSCs, and it provides a useful insight into the synthesis of the next-generation of HTMs for PrSC application.

Water-soluble porphyrin-polyethylene glycol conjugates with enhanced cellular uptake for photodynamic therapy.

Water soluble porphyrins were designed and prepared by Williamson ether synthesis reaction between tetrakis(p-bromomethylphenyl)porphyrin and polyethylene glycol (PEG) for photodynamic therapy. The quantum yields for the generation of singlet oxygen of tetra-polyethylene glycol branched porphyrin shows above 80% in D2O. Luminescence of singlet state oxygen was observed from D2O solution under the single-photon excitation at 514 nm. In vitro test, cellular uptake efficiency has been enhanced by simple modification of molecular structure through changing the number of PEG unit without any support such as polymer-encapsulated inorganic nanoparticles.