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We have studied the characteristics of composites of an environmentally friendly water-soluble polythiophene sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate] (PTEBS) and TiO2. We observed that the ultraviolet-visible absorption spectrum of low molecular weight PTEBS is redshifted possibly due to the formation of aggregates. Cyclic voltammetry reveals the values of highest occupied molecular orbitals and lowest unoccupied molecular orbitals for PTEBS. A factor of 7 in photoluminescence quenching indicates that the exciton dissociation and charge separation occur successfully at the PTEBS:TiO2 (1:1 by weight) interface. This enhances the possibility that the separated charges will reach the electrodes before recombining. Scanning electron micrograph images show how the PTEBS and TiO2 are interconnected and form paths to the electrodes to improve charge transport. Photovoltaic devices with TiO2:PTEBS composite achieved an energy conversion efficiency of η=0.015%, a short circuit current of JSC=0.22 mA/cm2, an open circuit voltage of VOC=0.72 V, and a fill factor of FF=0.29 under ∼300 mW/cm2 white light illumination. [ABSTRACT FROM AUTHOR]

The reported efficiencies of pristine ZnO nanorod array (NRA)-based polymer-inorganic hybrid solar cells (HSCs) are normally lower than those of their pristine TiO 2 NRA-based counterparts. This difference typically results from the lower short-circuit current density ( J sc ) of the ZnO NRA device. This paper presents a comparative study of pristine ZnO and TiO 2 NRA-based HSCs. We investigate the morphological structure (length, diameter, number density, area of nanorod laterals), photovoltaic performance (current density-voltage J – V , external quantum efficiency EQE), and optoelectronic processes related to electron transfer (electron mobility μ e , electron diffusion length L D , electron lifetime τ e and electron transit time τ t related electron collecting efficiency η cc , electron injection η inj , surface potential SP, photoluminescence PL, bound charge pairs BCP) in HSCs, with ZnO and TiO 2 NRA as electron acceptor. Our comparative investigations reveal that the factors relating to the interface area, μ e , L D , and η cc are not the key factors responsible for the difference in the value of J sc in ZnO and TiO 2 NRA-based HSCs with the same device structure. In fact, the crucial step for a lower J sc in ZnO NRA-based HSCs than in TiO 2 NRA-based HSCs is attributed to the less efficient transfer of photo-generated electrons at the charge separation interface in ZnO NRA-based HSCs. Dynamic characterizations indicate that the transfer of interfacial photo-generated electrons in TiO 2 NRA-based HSCs is more efficient than ZnO NRA-based HSCs, and is confirmed by Kelvin probe force microscopy (KPFM) and PL studies. The reason for the better interface charge transfer property in MEH-PPV/TiO 2 NRA than that of in MEH-PPV/ZnO NRA is further investigated by Marcus model, we find that more trapped BCP states are generated in the ZnO NRA based HSCs, which resulting in lower interfacial electron injection efficiency from polymer to ZnO NRA. [ABSTRACT FROM AUTHOR]

Abstract: Open circuit voltage (V oc) and other photovoltaic parameters from fluorine tin oxide (FTO) P3OT/TiO2 composite solar cells have been investigated in comparison with those from the indium tin oxide (ITO) devices with the same device structure and fabrication process. From the experimental results, the performance of FTO-based devices is better than that of ITO devices in terms of V oc, short circuit current density (J sc), and power conversion efficiency. The origin of V oc and the higher V oc of FTO can be explained and estimated by metal–insulator–metal model with a non-ohmic cathode contact. [Copyright &y& Elsevier]

The J–V hysteresis effect has become a major factor restricting the development of PSC. The J–V hysteresis effect of the PSC is a combination of many factors and cannot be simply considered to be caused by a certain kind. The hysteresis-free PSC fabrication should be involved of many aspects. [Display omitted] • The internal and external factors that cause the J–V hysteresis phenomenon are discussed. • The abnormal hysteresis such as inverted hysteresis and tunneling hysteresis are summarized. • Various strategies to alleviate the J–V hysteresis in perovskite solar cells are summarized. • Insights into hysteresis-free device are proposed. Organic-inorganic hybrid perovskite solar cell (PSC) has received widespread attention due to its high efficiency, low cost, and easy fabrication process. However, the commercialization of PSC is still hindered due to their unstable properties. Current density-voltage (J–V) hysteresis is one of the instabilities that causes overestimate or underestimate of the real conversion efficiency of PSC, making it difficult to assess the true photovoltaic parameters. This review discusses the internal and external factors that causes the J–V hysteresis phenomenon and presents various strategies to alleviate the J–V hysteresis in PSC. This article also provides insights into the perspectives and critical challenges that are needed to address the hysteresis of PSC for further improvement of device performance. [ABSTRACT FROM AUTHOR]

• Nitrogen-doped graphene/ZnO nanorod composite (NG-ZnO NR) was used as electron transport layer (ETL) to replace TiO 2 for perovskite solar cells. • NG-ZnO NR composite based perovskite solar cells achieved a highest efficiency (16.82%) as compared to pristine ZnO nanorods (12.87%). • NG-ZnO NR composite promotes formation of uniform perovskite thin films with a high surface coverage area in comparison to pristine ZnO nanorods. • NG-ZnO NR composite based perovskite solar cells exhibited improved photocurrent and photon to electron conversion efficiency due to enhancement in light absorption. We demonstrate for the first time, the photovoltaic performance of perovskite solar cells (PSCs) by employing nitrogen-doped graphene/ZnO nanorod nanocomposites (NG-ZnO NR NCs) as an electron transport layer (ETL). A series of PSCs are fabricated by varying the NG concentration from 0 to 1 wt% with an increment of 0.2 wt% in ZnO NRs having a device structure of FTO/NG-ZnO NR NCs/CH 3 NH 3 PbI 3 /Spiro-MeOTAD/Ag. The perovskite films grown on NG-ZnO NR NCs exhibited a uniform film with high surface coverage area with an improved crystallinity. By employing photoluminescence measurements, it was found that NG-ZnO NR NCs reduced the interfacial resistance by improving charge carrier extraction, which is in correlation with an improvement in photocurrent and fill factor in the corresponding devices. At an optimized concentration of NG (0.8 wt%) in ZnO NRs, PSCs obtained an improvement in photocurrent from 17.38 mA/cm2 to 21.98 mA/cm2 and the power conversion efficiency from 12.87% to 16.82%, respectively. [ABSTRACT FROM AUTHOR]

Efficiency of earth abundant and pure sulfide kesterite Cu-Zn-Sn-S (CZTS) solar cell has been stagnant around 9.4% for years, while its counterpart Cu-In-Ga-Se (CIGS) reports an efficiency of more than 22%. Low open circuit voltage (VOC) is the major challenging factor for low efficiency due to severe nonradiative interface recombinations. The existence of higher defect states at the conventional CZTS-CdS interface due to undesirable energy level alignment and lattice misfit promotes trap-assisted recombinations and results in low VOC. In this work, amorphous TiO2 (E g = 3.8 eV) is proposed as a promising substitute to the conventional and low bandgap CdS (E g = 2.4 eV) layer. The surface and interface of the CZTS-TiO2 layer were investigated using X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The result reveals favorable "spike"-like conformations at the CZTS-TiO2 interface with a conduction band offset value of 0.17 eV. The nanoscale probing of the interface by Kelvin probe force microscopy across CZTS-TiO2 layers shows a higher potential barrier for interface recombination at CZTS-TiO2 in contrast to the conventional CZTS-CdS interface. Finally, the fast decay response and lower persistent photoconductivity of photogenerated carriers for CZTS-TiO2 heterojunction based photodetectors further validate our results. The energy level alignment and nanoscale interface studies signify TiO2 as a promising alternate buffer layer for earth abundant CZTS solar cells. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cell (DSSC) offers an efficient and easily implemented technology for future energy supply. Compared to conventional silicon solar cells, it provides comparable power conversion efficiency (PCE) at low material and manufacturing costs. DSSC materials such as titanium oxide (TiO 2 ) are inexpensive, abundant and innocuous to the environment. Since DSSC materials are less prone to contamination and processable at ambient temperature, a roll-to-roll process could be utilized to print DSSCs on the mass production line. DSSCs perform better under lower light intensities, which makes them an excellent choice for indoor applications. Due to the advancement of molecular engineering, colored and transparent thin films have been introduced to enhance the aesthetic values. Up to now, such benefits have attracted considerable research interests and commercialization effort. Here, this review examines advanced techniques and research trends of this promising technology from the perspective of device modeling, state-of-art techniques, and novel device structures. [ABSTRACT FROM AUTHOR]

Novel anthracene-bridged carbazole organic dyes (designated ML4 and ML5) were synthesized using the Suzuki coupling reaction. These dyes were designed to be donor-π-conjugation-acceptor sensitizers for dye-sensitized solar cells, where the carbazole moiety acts as the donor, the anthracene moiety provides the π-conjugation, and the cyano acrylic acid acts as the acceptor. Solar cells were fabricated with ML4 and ML5 alone with low power conversion efficiencies, but they were also used as co-sensitizers with N719, improving the efficiency of the dye-sensitized solar cells produced by ~3% and ~10%, respectively. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Pseudo-supercapacitors have been pursued to realize high energy densities to compete with batteries. However, supercapacitor based on carbon fails to achieve the desired high energy density due to the surface oriented pseudocapacitive behavior. Here we report intercalated pseudocapacitive charge storage in carbon tubes derived from mushroom, which owns a unique morphology consisting of mesoporous, multi-layered, and functional architecture decorated with heteroatoms. This unique naturally gifted structure offers exceptional redox active sites than traditional carbons delivering high-rate pseudocapacitive behavior with the highest gravimetric and volumetric capacitances of 995 F g−1 and 895 F cm−3 respectively. Additionally, stable and remarkable volumetric energy densities of 198 Wh L−1 at 560 W L−1 in an ionic electrolyte and 26 Wh L−1 at power density of 2–200 kW L−1 in an aqueous electrolyte are achieved. Overall, this investigation highlights a novel avenue for emerging next generation of sustainable high-performance energy storage devices. [Display omitted] • The multi-layered, mesoposous, functional carbon tubes with a density of 1 g cm−3 is derived from Mushroom. • We report a high gravimetric and volumetric capacitance of 995 F g−1 and 895 F cm−3 respectively. • The cyclic performance has emphasized increasing capacitance up to 15000 cycles and sustained up to 30000 cycles. • The stable volumetric energy density 26 Wh.L−1 at a power densities from 2 to 200 kW L−1 in an aqueous electrolyte. • The 180 Wh.L−1 at 2360 W L−1 in an ionic electrolyte directs potential automobile application. [ABSTRACT FROM AUTHOR]

4 H -Cyclopenta[2,1-b:3,4-b′]dithiophen-4-one (CPDTO), CPDTO ketal (CPDTO-k) and their oligomers have been synthesized and their optical absorption, fluorescent, electrochemical properties are characterized. Structure optimization and time-dependent energy calculation have been carried out for (CPDTO-k) 1,2,3,6 and (CPDTO) 1,2,3,6 using the B3LYP functional and standard split valence plus polarization basis set 6-31G(d,p) in the DFT formalism. The pi conjugation between carbonyl oxygen and thiophene, which is orthogonal to the backbone conjugation, is evident from the DFT calculation and analysis, and is responsible for the observed slower narrowing of bandgaps ( E g ) of CPDTO oligomers with increasing number of repeat units. The orthogonal conjugation also leads to different distribution of LUMO from that of HOMO and makes CPDTO oligomers weak in the lowest energy absorption. Enhanced intensity and red-shifted peak wavelength of the lowest energy UV–vis absorption of CPDTO film suggest the presence of strong intermolecular interactions among CPDTO molecules in the solid state, which may explain why the bandgap (1.1–1.2 eV) reported for the electrochemically deposited CPDTO homopolymer film is significantly lower than the bandgap (1.5–1.7 eV) estimated in this study for PCPDTO chloroform solution from the E g s of CPDTO oligomers. [ABSTRACT FROM AUTHOR]

In this paper, fully solution-processed organic solar cells were fabricated on prepurchased tin-doped indium oxide (ITO)-coated glass using the inverted architecture. Solution-processed electrodes consisting of ITO nanoparticle, silver (Ag) nanowire, or Ag nanoparticle films were used as the anode in the devices. Electrode deposition for solution-processed components was accomplished by using a commercially available airbrush with compressed dry nitrogen as the carrier gas. Morphologies of the deposited electrodes and the solution-processed electron blocking layer can be seen as topography images using atomic force microscopy. Cells fabricated with a solution-processed electrode show comparable device performances to that of an evaporated electrode using a similar structure. [ABSTRACT FROM AUTHOR]

It was found that the output power of the distributed feedback fiber lasers would be improved after annealing or left unused for several days after the laser had been fabricated, and the output of the fundamental mode would not increase but be clamped while the ±1 order modes would be predominant with the enhancement of the coupling coefficient during the fabrication. The paper discussed the influence of UV-induced fiber loss on the fiber phase-shifted DFB lasers. Due to the gain saturation and fiber internal loss, which included the temperament loss and permanent loss, there was an optimum coupling coefficient for the DFB fiber lasers that the higher internal fiber loss corresponded to the lower optimum values of coupling coefficient. [Copyright &y& Elsevier]

Photovoltaic power‐conversion systems can harvest energy from sunlight almost perpetually whenever sunrays are accessible. Meanwhile, as indispensable energy storage units used in advanced technologies such as portable electronics, electric vehicles, and renewable/smart grids, batteries are energy‐limited closed systems and require constant recharging. Fusing these two essential technologies into a single device would create a sustainable power source. Here, it is demonstrated that such an integrated device can be realized by fusing a rear‐illuminated single‐junction perovskite solar cell with Li4Ti5O12‐LiCoO2 Li‐ion batteries, whose photocharging is enabled by an electronic converter via voltage matching. This design facilitates a straightforward monolithic stacking of the battery on the solar cell using a common metal substrate, which provides a robust mechanical isolation between the two systems while simultaneously providing an efficient electrical interconnection. This system delivers a high overall photoelectric conversion‐storage efficiency of 7.3%, outperforming previous efforts on stackable integrated architectures with organic–inorganic photovoltaics. Furthermore, converter electronics facilitates system control with battery management and maximum power point tracking, which are inevitable for efficient, safe, and reliable operation of practical loads. This work presents a significant advancement toward integrated photorechargeable energy storage systems as next‐generation power sources. [ABSTRACT FROM AUTHOR]

One‐dimensional (1D) nanostructured oxides are proposed as excellent electron transport materials (ETMs) for perovskite solar cells (PSCs); however, experimental evidence is lacking. A facile hydrothermal approach was employed to grow highly oriented anatase TiO2 nanopyramid arrays and demonstrate their application in PSCs. The oriented TiO2 nanopyramid arrays afford sufficient contact area for electron extraction and increase light transmission. Moreover, the nanopyramid array/perovskite system exhibits an oriented electric field that can increase charge separation and accelerate charge transport, thereby suppressing charge recombination. The anatase TiO2 nanopyramid array‐based PSCs deliver a champion power conversion efficiency of approximately 22.5 %, which is the highest power conversion efficiency reported to date for PSCs consisting of 1D ETMs. This work demonstrates that the rational design of 1D ETMs can achieve PSCs that perform as well as typical mesoscopic and planar PSCs. [ABSTRACT FROM AUTHOR]

One‐dimensional (1D) nanostructured oxides are proposed as excellent electron transport materials (ETMs) for perovskite solar cells (PSCs); however, experimental evidence is lacking. A facile hydrothermal approach was employed to grow highly oriented anatase TiO2 nanopyramid arrays and demonstrate their application in PSCs. The oriented TiO2 nanopyramid arrays afford sufficient contact area for electron extraction and increase light transmission. Moreover, the nanopyramid array/perovskite system exhibits an oriented electric field that can increase charge separation and accelerate charge transport, thereby suppressing charge recombination. The anatase TiO2 nanopyramid array‐based PSCs deliver a champion power conversion efficiency of approximately 22.5 %, which is the highest power conversion efficiency reported to date for PSCs consisting of 1D ETMs. This work demonstrates that the rational design of 1D ETMs can achieve PSCs that perform as well as typical mesoscopic and planar PSCs. [ABSTRACT FROM AUTHOR]

In recent years, hybrid perovskite solar cells (HPSCs) have received considerable research attention due to their impressive photovoltaic performance and low‐temperature solution processing capability. However, there remain challenges related to defect passivation and enhancing the charge carrier dynamics of the perovskites, to further increase the power conversion efficiency of HPSCs. In this work, the use of a novel material, phenylhydrazinium iodide (PHAI), as an additive in MAPbI3 perovskite for defect minimization and enhancement of the charge carrier dynamics of inverted HPSCs is reported. Incorporation of the PHAI in perovskite precursor solution facilitates controlled crystallization, higher carrier lifetime, as well as less recombination. In addition, PHAI additive treated HPSCs exhibit lower density of filled trap states (1010 cm−2) in perovskite grain boundaries, higher charge carrier mobility (≈11 × 10−4 cm2 V−1 s), and enhanced power conversion efficiency (≈18%) that corresponds to a ≈20% improvement in comparison to the pristine devices. [ABSTRACT FROM AUTHOR]

CsPbI 2 Br inorganic perovskite has been considered as a promising candidate for application in photovoltaic devices due to its high thermal stability and reasonable bandgap of 1.92 eV. However, CsPbI 2 Br perovskite is sensitive to moisture, which remarkably deteriorates the stability of CsPbI 2 Br perovskite solar cells under the ambient conditions. Here, by using hydrophobic poly(3-hexylthiophene) (P3HT) layer in conjunction with multi-walled carbon nanotubes (MWCNTs) as the hole transporting layer, we develop a stable and high-performance carbon electrode-based CsPbI 2 Br inorganic perovskite solar cell (PSC). The P3HT-MWCNTs composites not only can prevent moisture ingress but also enhance the holes extraction and transport. A conversion efficiency up to 10.01% with a stabilized efficiency of 8.85% is achieved for the champion device. In addition, the as-prepared carbon electrode-based CsPbI 2 Br PSC exhibits an excellent long-term stability which retains ∼85% of its initial value over 240 h under the ambient conditions (∼35% R.H.) without encapsulation. [ABSTRACT FROM AUTHOR]

Carbon-based CsPbBr 3 perovskite solar cell is an emerging inorganic perovskite solar cell with the advantages of simple fabrication process and excellent stability. However, power conversion efficiency of carbon-based CsPbBr 3 perovskite solar cells is still unsatisfactory up to now, as the direct contact of the CsPbBr 3 with carbon is plagued with interfacial recombination sites and undesirable hole extraction barrier. Here, we report an effective strategy that employs poly (3-hexylthiophene) (P3HT) to modify the CsPbBr 3 /carbon interface in carbon-based CsPbBr 3 perovskite solar cells and enable higher efficiency. The systematic tests and analyses demonstrate that the P3HT interlayer can remarkably suppress the charge recombination and enhance the hole extraction capability via formation of favorable energy level alignment between CsPbBr 3 film and carbon electrode, and passivation of the surface defect states of CsPbBr 3 film. As a result, the carbon-based CsPbBr 3 perovskite solar cell with P3HT interlayer achieves a high conversion efficiency of 6.49%, exhibiting an increase by 27% compared to pristine device. Moreover, the carbon-based CsPbBr 3 perovskite solar cells with P3HT interlayer exhibits excellent stability in ambient air with almost no change in the power conversion efficiency of the unsealed device over 40 days. • P3HT is employed to modify the CsPbBr 3 /carbon interface in carbon-based CsPbBr 3 PSCs. • P3HT remarkably suppress the charge recombination and enhance the hole extraction. • The device with P3HT shows an efficiency of 6.49%, increasing by 27% over pristine one. [ABSTRACT FROM AUTHOR]

The present study is focused on a relatively new class of solid-state lithium halide electrolytes with antiperovskite crystal structure that are designed to alleviate safety concerns related to conventional lithium-ion batteries. The solid-state Li 3 ClO electrolyte membranes were produced by a casting/delamination method and deposited on a graphite-based working electrode. The electrolyte charge transfer resistances, electrochemical performance, and chemical stability in a half-cell configuration were evaluated over a broad temperature range from room temperature up to 100 °C. The electrochemical cells with lithium metal as a reference electrode demonstrated linear Arrhenius behavior in the temperature range of 25–100 °C confirming the absence of phase transformations. Cyclic voltammetry at 50 °C and 100 °C confirms that the electrochemical cell performance during lithiation/delithiation from 0.05 to 1.00 V is reproducible within at least 100 cycles. The solid-state electrolyte electrochemical stability in contact with lithium metal is confirmed for the first time by demonstrating the constant values of charge transfer resistances during charge/discharge operations in 575 cycles at 50 °C and 1/5 C -rate. Transport of lithium ions between the lithium metal and Li 3 ClO electrolyte in contact with a graphite working electrode provides evidence that lithium halide antiperovskites can serve as effective and electrochemically stable electrolytes for a new generation of all-solid-state lithium-ion or lithium metal batteries. Image 1031 • A solid-state electrolyte with antiperovskite structure was tested in a half-cell vs. lithium anode. • Electrolyte chemical stability in presence of Li-metal at 50 °C is confirmed by AC impedance. • Continuous cycling within 6 months at 50 and 100 °C demonstrate >80% specific capacity retention. [ABSTRACT FROM AUTHOR]

If counter electrodes (CEs) could also contribute to light harvesting in dye‐sensitized solar cells (DSSCs), then the power conversion efficiency (PCE) of DSSCs would be further boosted without changing the device structure. Nearly monodispersed Ag2Se nanocrystals with a bandgap of 1.62 eV (∼765 nm) were synthesized via a one‐pot process, and Ag2Se CEs were fabricated by using a spin‐coating and annealing process. Incident photon‐to‐current conversion efficiency and photocurrent spectra indicated that Ag2Se CEs can generate the electricity by harvesting more visible light, which could not be absorbed by dye‐sensitized photoanodes. Thus, compared to Pt CE (7.57 %), the DSSC based on Ag2Se CE exerted a higher PCE of 8.06 %. The development of photovoltaic CEs may offer an alternative way to promote the performance and competitiveness of DSSCs. Photovoltaic counter electrodes not only catalyse I3− reduction, but also harvest transmitted photons of photoanodes to increase the photocurrent of DSSCs (see figure). This offers an alternative method for enhancing the performance and competitiveness of DSSCs. [ABSTRACT FROM AUTHOR]

Herein, we clearly demonstrate that the inclusion of the organic solid additive (2,3-dihydroxypyridine, DOH) into the poly(diketopyrrolopyrrole-terthiophene) (PDPP3T) and phenyl-C 61 -butyric acid methyl ester (PCBM) (PDPP3T:PCBM) photoactive blend system alters the nanoscale morphology and enhances the photovoltaic (PV) performance of the inverted bulk heterojunction (BHJ) based polymer solar cells (PSCs). The influence of DOH additive casted PDPP3T: PCBM thin films on the optical, morphology and structural features is evaluated and correlated with PV characteristics. Topography images through atomic force microscopy reveal that the incorporation of DOH into PDPP3T: PCBM induces a finer nanoscale phase segregation between polymer and fullerene domains with fibrillar morphology. The PV performance of the DOH processed PDPP3T: PCBM devices is evaluated by current-voltage (J-V) characteristics and compared with pristine and 1, 8-diiodooctane (DIO) modified PDPP3T: PCBM devices. Interestingly, the incorporation of DOH (0.5 wt%) into PDPP3T: PCBM device witnessed the best PCE of 6.36%, which is significantly higher (69.1%) than that of the reference (3.76%). This significant enhancement in the performance of the device is mainly attributed to a dramatic increase in the short-circuit current density and fill-factor due to the improved bicontinuous interpenetrated phase separation and balanced charge transport. In addition, the measurements on photo-induced charge carrier extraction by linearly increasing voltage reveal that DOH incorporated devices exhibit higher mobility and charge carrier density as compared to those of pristine modified BHJ PSCs. The presence of vicinal functional groups in DOH contributes to the possible molecular level interactions with the blend components and accounts for the morphology and device performance enhancements. [ABSTRACT FROM AUTHOR]

We successfully combined electrospinning with in situ polymerization methods to synthesize the PANI-coated ZnFe 2 O 4 nanofibers which possess the abundant pore structure. The lithium storage properties of PANI-coated ZnFe 2 O 4 nanofibers as anode materials for lithium-ion batteries have been discussed for the first time. PANI nanoparticles were directly coated on the surface of the ZnFe 2 O 4 nanofibers, increasing the electrical conductivity, and also acting as the protect shell to enhance the mechanical strength of material. The electrochemical performance showed that 15% PANI incorporated ZnFe 2 O 4 composite nanofibers (ZP-15) exhibited the highest reversible capacity of 1142 mAhg −1 after 50 cycles, which was much higher than that of pure ZnFe 2 O 4 nanofibers (628 mAhg −1 ), 10% PANI incorporated ZnFe 2 O 4 composite nanofibers (ZP-10, 975 mAhg −1 ), and 20% PANI incorporated ZnFe 2 O 4 composite nanofibers (ZP-20, 536 mAhg −1 ). Additionally, the ZP-15 composite nanofibers achieved outstanding cycling rate capacity of 852, 738, 609 and 539 mAhg −1 with current densities range from 500 to 5000 mA g −1 , and exhibited a specific capacity of 1082 mAhg −1 when the current reverted to 50 mA g −1 from the high rate charge-discharge cycles. The enhanced electrochemical performance of PANI-coated ZnFe 2 O 4 nanofibers can be attributed to the PANI providing a highly electrical conductive medium, which can promote electron transfer and facilitate the Li + transport in the lithiation/delithiation process, also can reduce self-discharge; moreover, the PANI layer covered on the surface of ZnFe 2 O 4 nanofibers can be as buffer matrix to restrain the stress of volume expansion to get stable structure. [ABSTRACT FROM AUTHOR]

In this work, the energy and flux of high energetic ions were controlled by RF superimposed DC sputtering process to increase the grain size and suppress grain boundary potential with minimum residual stress in Al doped ZnO (AZO) thin film. AZO thin films were deposited at different RF/(RF + DC) ratios by keeping total power same and were investigated for their electrical, optical, structural and nanoscale grain boundaries potential. All AZO thin film showed high crystallinity and orientation along (002) with peak shift as RF/(RF + DC) ratio increased from 0.0, pure DC, to 1.0, pure RF. This peak shift was correlated with high residual stress in as-grown thin film. AZO thin film grown at mixed RF/(RF + DC) of 0.75 showed high electron mobility, low residual stress and large crystallite size in comparison to other AZO thin films. The nanoscale grain boundary potential was mapped using Kelvin Probe Force Microscopy in all AZO thin film and it was observed that carrier mobility is controlled not only by grains size but also by grain boundary potential. The XPS analysis confirms the variation in oxygen vacancies and zinc interstitials which explain the origin of low grain boundaries potential and high carrier mobility in AZO thin film deposited at 0.75 RF/(RF + DC) ratio. This study proposes a new way to control the grain size and grain boundary potential to further tune the optoelectronic-mechanical properties of AZO thin films for next generation flexible and optoelectronic devices. [ABSTRACT FROM AUTHOR]

Hierarchical CuInS 2 (H-CuInS 2 ) was synthesized with the induction of histidine by the solverthermal method. The factors such as the category of the amino acid, the molar-quantity of histidine, the solvent, reaction time and reaction temperature were observed. The products were characterized by scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and ultraviolet-visible absorption spectrum. The results showed that, histidine is proven to be effect to synthesize the uniform flower-like chalcopyrite H-CuInS 2 in the solvent of N,N-dimethyl formamide at 180 °C for 24 h, which is originated from the strong coordinate ability of histidine. The change in the molar-quantity of histidine would result in the obviously different sizes and micro-structures of H-CuInS 2 , contributing to the different light-harvesting ability and fluorescence quenching efficiency to poly (2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene) (MEH-PPV). As a result, polymer solar cells with MEH-PPV and different H-CuInS 2 displayed structure-dependent device performances, device based on small-sized H-CuInS 2 obtained higher energy conversion efficiency of 0.59% under the monochromatic illumination of 15.85 mW/cm 2 with wide spectrum response from 300 to 900 nm. [ABSTRACT FROM AUTHOR]

A series of novel coumarin pyrazoline moieties combined with tetrazoles, 3-(1-phenyl-4-(1H-tetrazol-5-yl)-1H-pyrazol- 3-yl)-2H-chromen-2-one, 6-chloro-3-(1-phenyl-4-(1H-tetrazol- 5-yl)-1H-pyrazol-3-yl)-2H-chromen-2-one, 6-bromo-3-(1-phenyl- 4-(1H-tetrazol-5-yl)-1H-pyrazol-3-yl)-2H-chromen-2-one and 6-bromo-3-(1-(4-bromophenyl)-4-(1H-tetrazol-5-yl)-1H pyrazol- 3-yl)-2H-chromen-2-one 7(a-d), were designed and synthesized. Single crystal X-ray diffraction and their interactions were studied by Hirshfeld surface analysis. Thermal stabilities and electrochemical properties of these compounds were examined from differential scanning calorimetry (DSC), thermogravimetric (TGA) and cyclic voltammetric (CV) studies. Their spectroscopic properties were analyzed in various alcohols and general solvents by UV-Vis absorption, fluorescence and time-resolved spectroscopy. In addition, the ground and excited state electronic properties were investigated using density functional theory (DFT). The calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and energy band gap (Eg) values have revealed the effect of substitution of halogens. The substitution has equally affected the ground and excited states of 7(a-d) compounds. The solvatochromism on absorption, fluorescence spectra and fluorescence lifetimes of these compounds was investigated. All these results showed the chromen-2-one of pyrazoline tetrazole derivatives could play an important role in photonic and electronic devices. [ABSTRACT FROM AUTHOR]

We investigated the role of a functional solid additive, 2,3-dihydroxypyridine (DHP), in influencing the optoelectronic, morphological, structural and photovoltaic properties of bulk-heterojunction-based polymer solar cells (BHJ PSCs) fabricated using poly(3-hexylthiophene): indene-C60 bisadduct (P3HT:IC60BA) photoactive medium. A dramatic increase in the power conversion efficiency (~20%) was witnessed for the BHJ PSCs treated with DHP compared to the pristine devices. A plausible explanation describing the alignment of pyridine moieties of DHP with the indene side groups of IC60BA is presented with a view to improving the performance of the BHJ PSCs via improved crystalline order and hydrophobicity changes. [ABSTRACT FROM AUTHOR]

In this paper, effect of titanium dioxide (TiO 2 ) nanoparticles (NPs) on newly synthesized phenothiazine dye i.e., ( Z )-2-cyano-3-(10-heptyl-10 H -phenothiazin-7-yl) acrylic acid (CPTA dye) has been studied using spectroscopic techniques such as absorption, fluorescence and electrochemical. Absorption spectra of CPTA dye in the presence of TiO 2 appears broadened without any shift in the absorption peaks which suggests possible interactions between the CPTA dye and TiO 2 NPs and absence of complex formation. These inferences were validated by determining association constant ( k a ) according to Benesi–Hildebrand theory. In order to see the role of fluorescence quenching, S-V theory was invoked, it was observed that phenomenon of quenching follows dynamic or collisional process under both steady and transient states. Experimentally determined magnitude of bimolecular quenching rate parameter is equal to the order of maximum collisional quenching rate parameter. Role of energy transfer between CPTA dye and TiO 2 NPs has been discussed using Rehm-Weller theory. From this it reveals that electron transfer process is more pronounced under more polar solvent (Methanol) than less polar solvent (ethyl acetate). Electron transfer mechanism has been exploited in solar energy harvesting applications by fabricating solar cell sensitized by CPTA dye. From this, it was observed that the efficiency and fill factor of fabricated DSSC was 2.15% and 0.58 respectively under optimized conditions and solar harvesting property of newly synthesized phenothiazine derivative of CPTA dye is the first report. [ABSTRACT FROM AUTHOR]

Organic-inorganic perovskite cell has shown a great deal of interest in past few years due to its ability to achieve high power conversion efficiency (PCE). Use of charge transport layers such as n-type TiO 2 and p-type doped spiroOMeTAD in a n-i-p device architecture has shown enhanced perovskite solar cell device performance. Use of doped spiroOMeTAD as hole transport layer in the n-i-p device structure has been effective but possess disadvantages such as complex processing, use of corrosive additives, processing in ambient air for efficient hole doping. Here we report the study of solution processed benzodithiophene based polymer PBDTT-FTTE as an alternative hole transport layer to doped small molecule spiroOMeTAD. PBDT-FTTE doped with 3% DIO (diiodooctane) achieved PCE of 11.6% which was comparable to matching PCE of 11.6% obtained from using spiroOMeTAD as hole transport layer. We showed that unlike spiroOMeTAD, polymer PBDTT-FTTE is processed inside N 2 filled glove box and is easier to process as compared to spiroOMeTAD which requires processing in ambient humid air and is doped with additives mixed in corrosive solvent, causing degradation to perovskite layer underneath. [ABSTRACT FROM AUTHOR]

Solar cells become a viable energy source to charge lithium ion batteries. Here a simple and efficient photocharging design approach is demonstrated, where a promising low cost single junction solar cell such as perovskite solar cell or dye sensitized solar cell efficiently charges a Li4Ti5O12-LiCoO2 Li-ion cell using a DC-DC voltage boost converter. The converter boosts the low input voltage of a single junction solar cell to charge a lithium ion cell and offers advantages including maximum power point tracking of solar photovoltaics and overvoltage protection for the lithium ion cell. This is the first demonstration of this technology. This approach leads to the highest reported overall efficiency of 9.36% and average storage efficiency of 77.2% at 0.5 C discharge for a perovskite solar cell-converter charging. The high efficiency for the perovskite solar cell-converter charging is attributed to maximum power harvesting along with high power conversion efficiency of the perovskite solar cell and low potential polarization between the charge and discharge voltage plateaus for the Li4Ti5O12-LiCoO2 Li-ion cell. [ABSTRACT FROM AUTHOR]

A novel ordered Co/CMK-3 nanocomposite was successfully synthesized via the sonochemical method followed by carbonization process. The ordered Co/CMK-3 nanocomposite were characterized by X-ray diffraction, transmission electron microscopy and N 2 adsorption–desorption analysis techniques. The lithium storage properties shows that the Co/CMK-3 nanocomposites exhibit a large reversible capacity and good cycle stability with the capacity of 720 mAh g −1 after 50 cycles at a current rate of 50 mA g −1 , much higher than that of original CMK-3 electrode. The Co/CMK-3 nanocomposites also demonstrates an excellent rate capability with capacity of 479 mAh g −1 even at a current density of 1000 mA g −1 after 50 cycles. The improved lithium storage properties of ordered Co/CMK-3 nanocomposites can be attributed to the CMK-3 could restrain the aggregation of Co nanoparticles, the large surface area of the mesopores in which the Co nanoparticles are formed, as well as presence of Co which played the role of catalyst could promote the lithium storage reaction. [ABSTRACT FROM AUTHOR]

ABSTRACT A soluble 4H-cyclopenta[2,1- b;3,4- b′]dithiophene-4-one (CPDTO)-based polymer (C6-PCPDTO) has been synthesized from two monomers derived from nonalkylated CPDTO and didodecyl CPDTO (C12-CPDTO). Proton NMR, thermal analysis, UV-vis absorption, cyclic voltammetry, and XRD are used to characterize the polymer in solution and film. The new polymer has an optical bandgap of 1.28 eV in film, and has strong interchain interaction in chloroform solutions. The polymer contains a significant amount of homocoupled segments. The regular segments and homocoupled CPDTO segments render the polymer highly aggregating in solution. The non-planar homocoupled C12-CPDTO segments prevent the polymer from forming regular π-stacks, resulting in a low SCLC hole mobility (3.88 × 10−7 cm2V−1s−1). CV experiments show that C6-PCPDTO is stable in its oxidized and reduced states. Solar cell devices were fabricated from C6-PCPDTO2:PC60BM blends of different weight ratios. High PC60BM loading (80% or greater) was required for the devices to show measurable efficiency, indicating that the limited π-stacking of the polymer is not sufficient to cause effective phase separation. Further development of synthetic method is still needed to eliminate structural defects so that long-range ordered pi-stacking can be realized in the polymer for these applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1077-1085 [ABSTRACT FROM AUTHOR]

Raw bio oil includes multicomponents. In order to avoid the interference between complex reactions, the model compounds, instead of the real bio oil, have been widely used for the study of raw bio-oil upgrade. In this work, the hydrodeoxygenation (HDO) of raw pine pyrolysis bio oil was investigated at 200 °C using Pd/Zn synergistic catalysis under hydrogen pressures of 200, 300, and 400 psi, separately. The resulting product included gas, liquid, and coke. The gas was characterized using a gas chromatography. The liquid was characterized using a gas chromatography-mass spectrometry. The results showed that the HDO performance achieved promotion to some extent by the Pd/Zn synergistic catalysis compared with use of Pd/C or Zn2+, independently. The HDO also gave rise to improvements on physicochemical properties of bio oils. Notably, the highest water content (13.16 wt%) revealed that deoxygenation reaction could be promoted by Pd/Zn synergistic catalysis compared with use of Pd/C or Zn2+, independently. More importantly, the highest hydrocarbon yield (19.15% on the base of liquid part) could be obtained by the treatment of 300 psi pressure and 200 °C temperature over Zn/Pd/C synergistic catalysis. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Wurtz-stannite Cu2CdGeS4 nanocrystals were synthesized via a facile hot-injection method at a low temperature. They exhibited low charge transfer resistance at the electrolyte–electrode interface and high electrocatalytic activity for the reduction of I3− in dye-sensitized solar cells (DSSCs). Moreover, this DSSC showed a power conversion efficiency of 7.67%, comparable to the Pt-based device (7.54%). [ABSTRACT FROM AUTHOR]

ABSTRACT A new polymeric dyad of oligo-anthracene-block-poly(3-hexylthiophene) (Oligo-ANT- b-P3HT) has been synthesized as a donor-donor dyad building block for organic photovoltaics. The polymer dyad and oligomer of anthracene-9,10-diyl (Oligo-ANT) are prepared by Grignard Metathesis. The higher order of crystallinity and molecular chains ordering at solid phase reveal the intrinsic optical and electrical properties of polymeric dyad resulting in relatively higher light harvesting ability compared to the oligo(anthracene-9,10-diyl). The UV-visible spectrum of (Oligo-ANT- b-P3HT) in solution shows broad absorption with two sets of absorption from both anthracene and thiophene core units, covering a wide range of the visible spectrum. The test devices of the blends of polymeric dyad with fullerene C61 (PCBM) show improved photovoltaic performance with a power conversion efficiency of 3.26% upon subjecting to pre-fabrication thermal treatments. With optimized morphology of the interpenetrating network and the shorter fluorescence lifetime of the annealed dyad/PCBM blends, the effective charge transfer from the donor dyad to PCBM has evidenced. Thus, these studies will allow further synthetic advances to make potential high crystalline polymeric dyads with significantly improved light harvesting capability. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 3032-3045 [ABSTRACT FROM AUTHOR]

A simple dry physical grinding and solvent mixing approach was used to prepare tin selenide – multiwalled carbon nanotube (MWCNT) hybrid as an anode material for high performance lithium ion batteries (LIBs). The pure tin selenide and their composites with carbon black or graphene oxides were previously reported, however no other groups have reported tin selenide/MWCNT composite as anode materials for LIBs. The new hybrid had superior electrochemical cycling performance with higher reversible (lithiation) capacity of 882 to 651 mA hg −1 over 50 cycles compared to pure tin selenide (602 to 58 mAhg −1 ) or pure MWCNT (339 to 171 mAhg −1 ) electrodes. The enhanced performance of the tin selenide/MWCNT hybrid was attributed to various factors including alleviation of volume change of tin selenide during lithiation/delithiation by nanoscale network of MWCNT which helped to preserve the electrical connectivity between active particles, reversible decomposition of tin selenide, lithiation/delithiation of MWCNTs and conductive electronic transport pathways provided by MWCNTs. [ABSTRACT FROM AUTHOR]

Improved performance in the bulk heterojunction (BHJ) polymer solar cells (PSCs) can be achieved through multiple mechanisms by tuning the structure of the components and design architecture. Therefore, in this study, we designed and fabricated an electrostatically assembled contact interfacial layer utilizing the electrostatic interactions between positively charged poly(diallyldimethylammonium chloride) (PDDA) and negatively charged sulfonate ions in a polymer, i.e. toluene sulfonic acid incorporated self-doped polyaniline (SPAN(TSA − )) (designated as SPAN(TSA − )/EA − CIL). We investigated the influence of SPAN(TSA − )/EA − CIL on the photovoltaic performance of BHJ PSCs. We adopted a simple “dip-dry” technique to fabricate the SPAN(TSA − )/EA − CIL. Cyclic Voltammetry, X-ray photoelectron spectroscopy, Ultraviolet-visible spectroscopy, water contact angle measurements, electrochemical impedance spectroscopy and atomic force microscopy were employed to characterize the new SPAN(TSA − )/EA − CIL and to elucidate the associated enhancements in the photovoltaic performance. The fabricated PSCs with the SPAN(TSA − )/EA-CILs exhibited an improved photoconversion efficiency (PCE) through enhancement of both the short-circuit current density ( J SC ) and fill factor compared to the device consisting of only SPAN(TSA − ) or PEDOT:PSS. A plausible mechanism is presented here that explains the enhanced J SC and PCE in terms of transient dipole induction at the SPAN(TSA − )/EA-CIL surface. Interestingly, the PCE of devices based on ITO/SPAN(TSA − )/EA-CIL(1:1)/P3HT:PC 60 BM/Al and ITO/SPAN(TSA − )/EA-CIL(1:1)/PBDTTT-C-T:PC 70 BM/Al was enhanced by 13% (3.19–3.67%) and 10% (5.11–5.60%) compared to those of devices based on ITO/PEDOT:PSS/P3HT:PC 60 BM/Al and ITO/PEDOT:PSS/PBDTTT-C-T:PC 70 BM/Al, respectively. The present work thus identifies a novel class of low-temperature processable interface layer with a potential to fabricate highly efficient photovoltaic devices. [ABSTRACT FROM AUTHOR]

The current state-of-the-art dye loading process for modern dye-sensitized solar cells (DSCs), essentially unchanged for the last 24 years, entails dip-coating nanoporous TiO 2 photoelectrodes in a concentrated solution of dye for an average of 16 h. This process constitutes up to 80% of the fabrication time, leads to significant dye waste, and necessitates the use of organic solvents. A promising gas-phase deposition technique, coined Functionalized Carboxylate Deposition (FCD), was used to rapidly deposit a self-assembled monolayer of targeted α-carbon modified carboxylic acid containing dye molecules on TiO 2 photoelectrodes. The FCD process successfully reduced the dye loading time by 98% (i.e., 15–20 min compared to an average of 16 h). Moreover, the FCD-sensitized photoelectrodes produced DSCs with equivalent or higher efficiencies than dip-coating for the dyes used (both in this study and by other researchers). The performance of FCD dye sensitization in this study indicates its potential applicability as a foundational technology for rapid fabrication of efficient DSCs. [ABSTRACT FROM AUTHOR]

We report solution processed pristine diketopyrrolopyrrole (DPP) based polymer (PDPP3T) as hole transport layer (HTL) for perovskite (CH 3 NH 3 PbI 3 ) solar cells. The pristine PDPP3T based perovskite solar cells achieved comparable photovoltaic performance (12.32%) as that (12.34%) of doped spiro-OMeTAD based cells. After exposing to air having 40% relative humidity at room temperature, PDPP3T based perovskite solar cells showed much slower degradation than spiro-OMeTAD cells. The PDPP3T based devices showed an efficiency decrease by 26.6% after being in air for 73 h and 60.6% for 172 h, while the spiro-OMeTAD cells exhibited a much larger efficiency decrease of 41.4% for 73 h and 82.9% for 172 h. The use of pristine PDPP3T does not require processing HTL in air and adding any additives such as lithium salt dissolved in acetonitrile, 4-tert-butylpyridine (TBP), which are needed for the spiro-OMeTAD HTL preparation. This prevents exposure of the perovskite layer to ambient air and avoids corrosion of perovskite layer by acetonitrile solvent and formation of PbI 2 .xTBP complex which leads to slow down the cell degradation and improves device stability. [ABSTRACT FROM AUTHOR]

As a kind of promising generation solar cells, the catalytic properties of counter electrodes (CEs) play a key factor on the performance of QDSSCs (quantum dot-sensitized solar cells) at present. Here, hierarchical Cu 7 S 4 nanotubes (Cu 7 S 4 -HNT) assembled by hexagonal nanoplates have been prepared by an in-situ growth route and etching process at room temperature. The formation mechanism of the unique morphology is also proposed. Because of the rapid diffusion of electrons and electrolyte, abundant catalytic sites and high stability, the as-prepared Cu 7 S 4 -HNT combined the characteristics of nanotube and hierarchical structure can improve the catalytic performance of CEs. QDSSCs based on the Cu 7 S 4 -HNT CEs possess a high power conversion efficiency of 4.53%, superior to those with the commonly used Cu 2 S/brass (3.3%) or the referenced Pt (1.79%) CEs. What's more, the Cu 7 S 4 -HNT CE still shows excellent stability in electrolyte after 1000 CV cycles. [ABSTRACT FROM AUTHOR]

It is generally believed that silver or silver-based compounds are not suitable counter electrode (CE) materials for dye-sensitized solar cells (DSSCs) due to the corrosion of the I−/I3− redox couple in electrolytes. However, Ag2S has potential applications in DSSCs for catalyzing I3− reduction reactions because of its high carrier concentration and tiny solubility product constant. In the present work, CE manufactured from Ag2S nanocrystals ink exhibited efficient electrocatalytic activity in the reduction of I3− to I− in DSSCs. The DSSC consisting of Ag2S CE displayed a higher power conversion efficiency of 8.40 % than that of Pt CE (8.11 %). Moreover, the devices also showed the characteristics of fast activity onset, high multiple start/stop capability and good irradiated stability. The simple composition, easy preparation, stable chemical property, and good catalytic performance make the developed Ag2S CE as a promising alternative to Pt CE in DSSCs. [ABSTRACT FROM AUTHOR]

In this work, we hypothesized and demonstrated a new strategy to tune/modulate the electrochemical, microstructural and opto-electronic properties based on the manipulation of the intentionally included external dopant ion (X − ) within the sulfonated polyaniline (SPANs). Through our new strategy, we developed a different type of SPANs comprising of internal (fixed) and external (mobile) dopant. The X − included SPANs were prepared through a sequential doping, dedoping and redoping processes and designated as SPAN-R (X − ) (where X − is the anion of toluene sulfonic acid (TSA) or camphor sulfonic acid (CSA) or napthalene sulfonic acid (NSA)) by modifying the structure of 4-aminodiphenylamine-2-sulfonic acid with additional polyaniline chains to accommodate X − . SPAN-R(X − ) polymers were characterized by cyclic voltammetry, UV–visible spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Atomic force microscopy to elucidate the influence of X − on the electrical, optoelectronic, microstructural properties and surface properties on the performance characteristics of polymer solar cells (PSCs) fabricated with SPAN-R(X − ) as a buffer layer. The electrochemical band gap, degree of doping (DD), electrical conductivity and degree of crystallinity (CD) were evaluated and correlated to understand the influence of X − on them. The power conversion efficiency (PCE) of PSCs featuring SPAN-R(TSA − ) as a buffer layer showed a ~3.2 times improvement in the overall PCE, compared with the PSCs having pristine SPAN (not containing X − ) as a buffer layer and is higher than that of SPAN-R(CSA − ) and SPAN-R(NSA − ) based devices. The superior photovoltaic (PV) characteristics observed for SPAN-R(TSA − ) is due to the synergistic contributions from appropriate energy-level/work function alignment, higher conductivity, higher DD and induced molecular order with the photoactive layer. Importantly, PSCs with SPAN-R(X − ) buffer layer processed at low temperature (30 °C) (without thermal treatment) exhibited improved PV characteristics and better air-stability as compared to the device having poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) (thermally annealed at 150 °C) as buffer layer. As buffer layers, SPAN-R(X − ) polymers, containing fixed and mobile dopants, are most attractive because of low temperature processability and improved solar cell performance. [ABSTRACT FROM AUTHOR]

Inverted polymer solar cells (iPSCs) have shown a great potential in organic photovoltaics due to its enhanced stability and large-scale roll-to-roll processing. Metallated conjugated polymers also show promise as a donor material in the PSCs. In this paper, the role of solvents on the performance of inverted structure metallated PSCs was understood. Chlorobenzene (CB) and toluene were used as solvents to obtain the optimum morphology for improved device efficiency. To understand the charge transport properties and charge carrier lifetime in metallated polymer iPSCs, atomic force microscopy and transient photocurrent measurements were performed. The results showed that the CB as a solvent can improve the morphology of the active layer and enhance the performance of metallated iPSCs. [ABSTRACT FROM AUTHOR]

Porous hollow tin oxide (SnO2) nanofibers and their composite with titanium dioxide (TiO2) particles (Degussa P25) were investigated as a photoanode for dye-sensitized solar cells. Incorporation of TiO2 particles in porous hollow SnO2 fibers enhanced the power conversion efficiency ( \eta ) from 4.06% to 5.72% under 100-mW/cm ^{2} light intensity. The enhancement of efficiency was mainly attributed to increase in current density ( J_{\rm sc}$ ) and improvement in fill factor (FF). Increase in J_{\rm sc} was caused by higher dye loading as indicated by UV–Vis absorption spectra and the improvement in FF was attributed to faster charge transport time as obtained from transient analysis. The microstructure of SnO2 fibers was studied using transmission electron microscope, scanning electron microscope, and X-ray diffraction. The electron transfer and recombination life times were studied using transient analysis, whereas interfacial charge transfer was studied using electrochemical impedance spectroscopy. [ABSTRACT FROM AUTHOR]

In this paper, the role of fullerene loading on the nanomorphology and photovoltaic performance of alternating copolymer poly{2-octyldodecyloxy-benzo[1,2-b;3,4-b] dithiophene-alt-5,6-bis(dodecyloxy)-4,7bis(thiophen-2-yl)-benzo[c] [1,2,5]-thiadiazole} (PBDT-ABT-1) blend films was investigated. The morphology of blend films with different Phenyl C-60-butyric acid methyl ester (PCBM) mixing ratios and solvent additives was studied using atomic force microscopy (AFM) and energy-filtered transmission electron microscopy (EFTEM). AFM and EFTEM images showed difference in the intermixing of polymer with fullerene between 1:1, 1:2, and 1:3 weight ratios. Polymer/PCBM intermixed domain size increases with higher PCBM weight ratios. X-ray diffraction measurements on the pristine polymer and blend films cast without additives did not show any peaks, suggesting an amorphous nature of PBDT-ABT-1. EFTEM images from the donor/acceptor composite showed intermixed polymer–PCBM domains separated by the polymer boundary. Furthermore, EFTEM images for di-iodooctane (DIO) additive cast film revealed purer polymer domain. Photo-charge extraction by linearly increasing voltage measurement exhibited that charge extraction is highest in the nanomorphology sample with a weight ratio of 1:2, corresponding to the lowest bimolecular recombination and the highest charge carrier mobility. [ABSTRACT FROM AUTHOR]

By using a single host for both blue and orange phosphorescent dopants, a simple and efficient white organic light emitting-diode is reported. The dual-emissive-layer white device achieves a peak external quantum efficiency of 16.9 ± 0.9% and power efficiency of 44.1 ± 2.3 lm/W without out-coupling enhancement. Analysis of the device working mechanism determines that the blue dopant molecules can form a bridge to facilitate electron transport into the adjacent orange emitting-layer. The orange emission originates from both the direct electron trapping by the orange dopant and incomplete blue–orange energy transfer mechanisms. The origin of the voltage-dependent color shift of the device is quantitatively determined according to the working mechanism. Possible solution to reducing the color-shift is also provided based on the calculation and analytical results. [ABSTRACT FROM AUTHOR]

Non-edible sunflower oils that were extracted from sunflower residual wastes were catalytically cracked over a ZSM-5 catalyst in a fixed-bed reactor at three different reaction temperatures: 450°C, 500°C and 550°C. The catalyst was characterized using XRD, FT-IR, BET and SEM. Characterizations of the upgraded sunflower oils, hydrocarbon fuels, distillation residues and non-condensable gases were carried out. The effect of the reaction temperature on the yield and quality of liquid products was discussed. The results showed that the reaction temperature affected the hydrocarbon fuel yield but had a minor influence on its properties. The highest conversion efficiency from sunflower oils to hydrocarbon fuels was 30.1%, which was obtained at 550°C. The reaction temperature affected the component content of the non-condensable gases. The non-condensable gases generated at 550°C contained the highest content of light hydrocarbons (C 1 C 5 ), CO, CO 2 and H 2 . Compared to raw sunflower oils, the properties of hydrocarbon fuels including the dynamic viscosity, pH, moisture content, density, oxygen content and heating value were improved. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) semiconducting nanosheets have emerged as an important field of materials, owing to their unique properties and potential applications in areas ranging from electronics to catalysis. However, the controlled synthesis of ultrathin 2D nanosheets remains a great challenge, due to the lack of an intrinsic driving force for anisotropic growth. High-quality ultrathin 2D FeSe2 nanosheets with average thickness below 7 nm have been synthesized on large scale by a facile solution method, and a formation mechanism has been proposed. Due to their favorable structural features, the as-synthesized ultrathin FeSe2 nanosheets exhibit excellent electrocatalytic activity for the reduction of triiodide to iodide and low charge-transfer resistance at the electrolyte-electrode interface in dye-sensitized solar cells (DSSCs). The DSSCs with FeSe2 nanosheets as counter electrode material achieve a high power conversion efficiency of 7.53% under a simulated solar illumination of 100 mWcm-2 (AM 1.5), which is comparable with that of Pt-based devices (7.47 %). [ABSTRACT FROM AUTHOR]

Today's state-of-the-art phosphorescent organic light-emitting diodes (PhOLEDs) must rely on the host-guest doping technique to decrease triplet quenching and increase device efficiency. However, doping is a sophisticated device fabrication process. Here, a Pt(II)-based complex with a near unity photoluminescence quantum yield and excellent electron transporting properties in the form of neat film is reported. Simplified doping-free white PhOLED and yellow-orange PhOLED based on this emitter achieve rather low operating voltages (2.2-2.4 V) and very high power efficiencies of approximately 80 lm W−1 (yellow-orange) and 50 lm W−1 (white), respectively, without any light extraction enhancement. Furthermore, the efficient white device also exhibits high color stability. No color shift is observed during the entire operation of the device. Analysis of the device's operational mechanism has been postulated in terms of exciton and polaron formation and fate. It is found that using the efficient neat Pt(II)-complex as a homogeneous emitting and electron transporting layer and an ambipolar blue emitter are determining factors for achieving such a high efficiency. [ABSTRACT FROM AUTHOR]

Abstract: A method for fabrication of highly transparent platinum counter electrodes (CEs) has been developed based on spray coating of Pt nanoparticles (NPs) on hot substrates. This method leads to 86% reduction in Pt consumption reducing the Pt cost per peak watt of counter electrode from $0.79/Wp down to $0.11/Wp compared to the conventional Pt counter electrodes made by sputter deposition. The simplicity and low cost of this method provide a basis for an up-scalable fabrication process. The Pt NP layer is over 88% transparent, leading to overall transparency of 80% when incorporated with indium tin oxide/glass substrates for functional counter electrodes. This counter electrode exhibits a large surface area and high catalytic activity, comparable to that of the conventional opaque CEs. Semi-transparent dye-sensitized solar cells fabricated based on this counter electrode showed 6.17% power conversion efficiency. [Copyright &y& Elsevier]

Abstract: Cationic iridium(III) complexes with 1,10-phenanthroline (phen) derivatives containing oxadiazole-triphenylamine, oxadiazole or triphenylamine unit used as neutral auxiliary ligands, with the formula of [Ir(ppy)2(op-phen)][PF6] (C1), [Ir(ppy)2(o-phen)][PF6] (C2), and [Ir(ppy)2(p-phen)][PF6] (C3) (ppy = 2-phenylpyridine) were synthesized, respectively. The complexes exhibit high thermal stability and were used as phosphorescent dopants in polymer light-emitting diodes (PLEDs) with the configuration of ITO/PEDOT: PSS/PVK (70): PBD (30): complex (x, wt.%)/TPBI/CsF/Al. The complexes C1, C2 and C3 exhibit high electroluminescent performances with the maximum luminance efficiencies of 30.6 cd/A, 28.4 cd/A and 26.3 cd/A, respectively. The Commission Internationale de L'Eclairage (CIE) color coordinates of all complexes are (0.41, 0.55) corresponding to the yellow-green region. The complex C1 containing bipolar unit of oxadiazole-triphenylamine exhibits higher efficiency due to its balance of hole and electron fluxes. [Copyright &y& Elsevier]