To investigate the effects of copper (Cu), rice plant (Oryza sativa. L. var. MSE-9) was treated with different Cu concentrations (0, 10, 50 and 100μM) for 5 days in hydroponic condition. Gradual ...decrease in shoot and root growth was observed with the increase of Cu concentration and duration of treatment where maximum inhibition was recorded in root growth. Cu was readily absorbed by the plant though the maximum accumulation was found in root than shoot. Hydrogen peroxide (H2O2) production and lipid peroxidation were found increased with the elevated Cu concentration indicating excess Cu induced oxidative stress. Antioxidant enzymes superoxide dismutase (SOD), guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) and glutathione reductase (GR) were effectively generated at the elevated concentrations of Cu though catalase (CAT) did not show significant variation with respect to control. Ascorbate (ASH), glutathione (GSH) and proline contents were also increased in all the Cu treated plants compared with the control. SOD isoenzyme was greatly affected by higher concentration of Cu and it was consistent with the changes of the activity assayed in solution. The present study confirmed that excess Cu inhibits growth, induced oxidative stress by inducing ROS formation while the stimulated antioxidative system appears adaptive response of rice plant against Cu induced oxidative stress. Moreover proline accumulation in Cu stress plant seems to provide additional defense against the oxidative stress.
► Excess Cu negatively affects growth of the rice plant. ► Damage was more severe in root than shoot. ► Excess Cu led to oxidative stress in rice plant by inducing ROS generation. ► The plant tolerated the oxidative stress by increasing antioxidant defense system. ► Increased level of proline also reflects its association in tolerating the stress.
The diketopyrrolopyrrole-based copolymers PDPP-BBT and TDPP-BBT were synthesized and used as a donor for bulk heterojunction photovoltaic devices. The photophysical properties of these polymers ...showed absorption in the range 500−600 nm with a maximum peak around 563 nm, while TDPP-BBT showed broadband absorption in the range 620 − 800 nm with a peak around 656 nm. The power conversion efficiencies (PCE) of the polymer solar cells based on these copolymers and 6,6-phenyl C61 butyric acid methyl ester (PCBM) were 0.68% (as cast PDPP-BBT:PCBM), 1.51% (annealed PDPP-BBT:PCBM), 1.57% (as cast TDPP-BBT:PCBM), and 2.78% (annealed TDPP-BBT:PCBM), under illumination of AM 1.5 (100 mW/cm2). The higher PCE for TDPP-BBT-based polymer solar cells has been attributed to the low band gap of this copolymer as compared to PDPP-BBT, which increases the numbers of photogenerated excitons and corresponding photocurrent of the device. These results indicate that PDPP-BBT and TDPP-BBT act as excellent electron donors for bulk heterojunction devices.
This paper describes the application of electrophoretic deposition for air pollution removal using anatase as a photoactive coating. In this study, the anatase form of TiO
2
has been applied to (1) ...fluorine-doped tin oxide (FTO)-coated glass; (2) 304L stainless steel; and (3) titanium substrates using isopropanol and acetylacetone-based solutions at 20, 40, 60 and 80 V. In order to increase the strength of the substrate–anatase interface without transforming the phase into rutile, samples were calcined at 450 °C for 2 h. The resulting coatings were characterised by Raman spectroscopy, X-ray diffraction, non-contact optical profilometry and scanning electron microscopy. The photocatalytic activity of the deposited coatings were evaluated in the gas phase for nitrogen dioxide (NO
2
) removal by electron ionisation mass spectrometry, whilst irradiated by light of wavelength 376–387 nm for 100 min. Anatase phase titania supported on a FTO-coated glass substrate showed the highest photoactivity for NO
2
remediation. This was attributed to the formation of a three-dimensional nanostructure with properties determined by the deposition conditions. This work provides routes for the development of low-cost and large area photoactive coatings for pollution control.
Graphical Abstract
A Ru-based dye K-60 and a metal free D-A organic dye Y1 have been employed for the fabrication of a mixed dye sensitized solar cell (MDSSCs) system. The photophysical and electrochemical ...characterization revealed that the energy levels and absorption profiles of both the dyes are suitable for co-sensitization. We have adopted the cocktail co-sensitization method, in which a TiO
2
photoanode was immersed into a mixed solution of K-60 and Y1 for 12 h. The DSSC sensitized with a mixture of K-60 and Y1 exhibited an overall PCE of 8.19% (
J
sc
= 14.95 mA cm
−2
,
V
oc
= 0.59 V and FF = 0.71) higher than that for DSSC sensitized with a single K-60 dye (PCE = 6.26%). The higher PCE of the DSSC sensitized with K-60 + Y1 is attributed to the enhancement in both
J
sc
and FF and related to the high and broader IPCE spectra.
A Ru-based dye K-60 and a metal free D-A organic dye Y1 have been employed for the fabrication of a mixed dye sensitized solar cell (MDSSCs) system.
A new series of low band gap dyes,
C1,
C2 and
S, was synthesized. The quasi solid state DSSCs with dye
S showed an overall power conversion efficiency (PCE) of 4.17% which is higher than the other ...dyes (3.26% for
C2 and 2.59% for
C1). By increasing the molecular weight of poly(ethylene oxide) in electrolyte, the PCE of the DSSC based on
S increased up to 4.8%.
Display omitted
▶ A new series of low band gap photosensitizers for dye-sensitized solar cells (DSSCs). ▶ New dyes based on 2-styryl-5-phenylazo-pyrrole. ▶ Power conversion efficiency of 4.17% for dye
S which contains sulfonic acid anchoring group. ▶ Power conversion efficiency of 4.8% for dye
S by increasing the molecular weight of PEO in electrolyte.
A new series of low band gap dyes,
C1,
C2 and
S, based on 2-styryl-5-phenylazo-pyrrole was synthesized. These dyes contain one carboxy, two carboxy and one sulfonic acid anchoring groups, respectively. They were soluble in common organic solvents, showed long-wavelength absorption maximum at ∼620
nm and optical band gap of 1.66–1.68
eV. The photophysical and electrochemical properties of these dyes were investigated and found to be suitable as photosensitizers for dye sensitized solar cells (DSSCs). The quasi solid state DSSCs with dye
S showed a maximum monochromatic incident photon to current efficiency (IPCE) of 78% and an overall power conversion efficiency (PCE) of 4.17% under illumination intensity of 100
mW
cm
−2 (1.5
AM), which is higher than the other dyes (3.26% for
C2 and 2.59% for
C1). Even though dye
S contains one sulfonic acid anchoring group, the higher PCE for the DSSCs based on this dye has been attributed to the higher dye loading at the TiO
2 surface and enhanced electron lifetime in the device, as indicated by absorption spectra and electrochemical impedance spectra measurements. Finally, by increasing the molecular weight of poly(ethylene oxide) (PEO) in electrolyte, the PCE also increases up to 4.8% for the electrolyte with PEO molecular weight of 2.0
×
10
6. This improvement has been attributed to the enhancement in iodide ions diffusion due to the increase in free volume of polymer gel electrolyte.
Dye sensitized solar cells (DSSCs) and bulk heterojunction (BHJ) solar cells have been the subject of intensive academic interest over the past two decades, and significant commercial effort has been ...directed towards this area with the vison of developing the next generation of low cost solar cells. Materials development has played a vital role in the dramatic improvement of both DSSC and BHJ solar cell performance in the recent years. Organic conjugated polymers and small molecules that absorb solar light in the visible and near infrared (NIR) regions represent a class of emering materials and show a great potential for the use of different optoelectronic devices such as DSSCs and BHJ solar cells. This account describes the emering class of near infrared (NIR) organic polymers and small molecules having donor and acceptors units, and explores their potential applications in the DSSCs and BHJ solar cells.
Near‐infrared organic materials: Organic conjugated polymers and small molecules that absorb solar light in the visible and near‐infrared regions represents a class of emerging materials and show a great potential for the use of different optoelectronic devices such as DSSCs and BHJ solar cells. This review describes the emering class of near‐infrared organic polymers and small molecules having donor and acceptors units, and explores their potential applications in DSSCs and BHJ solar cells.
Three porphyrin dyes, P1, P2 and P3, bearing one, two and four pyridyl groups, respectively, in the mesopositions, acting as electron acceptor anchoring groups, were synthesized, characterized and ...investigated as sensitizers for the fabrication of dye sensitized solar cells (DSSCs). The overall power conversion efficiencies (PCEs) of DSSCs based on these dyes lay in the range 2.46-3.9% using a 12 mu m thick TiO sub(2) photoanode. Porphyrin P2 achieved the maximum performance, which can be rationalized by the high dye loading, efficient electron injection, dye regeneration process and longer electron lifetime, as demonstrated by the electrochemical impedance spectroscopy (EIS) measurements. The PCE of the DSSC based on the P2 sensitizer when the photoanode was treated with formic acid, showed an enhanced efficiency of 5.23%. This improvement, attributed to multifunctional properties such as higher dye uptake, reduced recombination process and enhanced charge collection efficiency. Deoxycholic acid (DCA) was also used as a coadsorbent in order to prevent dye aggregation and it was found that the PCE improved up to 6.12% for sensitizer P2 and the modified TiO sub(2) photoanode, which can be attributed to further improvement in the electron injection efficiency and charge collection efficiency.
We have designed and synthesized a new thiocyante-free ruthenium complex containing 2,6-bis(1-methylbenzimidazol-2-yl)pyridine, coded as SPS-G3, and it has been used as an efficient photosensitizer ...for dye-sensitized solar cells (DSSCs). Upon sensitization of SPS-G3 on nanocrystalline TiO2 film, the DSSC test cell yielded a large short-circuit photocurrent (16.15 mA cm–2), an open circuit voltage of 0.52 V, and a fill factor (FF) of 0.72, resulting in an overall power conversion efficiency (PCE) of 6.04% under simulated AM 1.5 solar irradiation (100 mW cm–2). DSSCs were prepared by adding various concentrations of multiwall carbon nanotubes (MWCNTs) (up to 0.5 wt %) into the TiO2 nanoparticles. Optimization of MWCNT concentration (0.3 wt %) lead to PCE values as high as 7.76%, while the test cells employing pure TiO2 photoanode obtained an efficiency of 6.04%. The results indicate that the PCE of MWCNTs/TiO2 composite DSSCs are dependent on the quantity of MWCNTs loading on the photoanodes. A small amount (0.3 wt %) clearly enhances the PCE of DSSC, while the excessive MWCNT loading lowers the photovoltaic performance of the DSSC. The increase in the PCE has been attributed to the decrease in charge-transport resistance, charge-transport time, and electron lifetime, which are estimated from electrochemical impedance spectra.
In this work diketopyrrolopyrrole based copolymers (PDPP-BBT and TDPP-BBT) containing a donor−acceptor structural unit have been explored as organic sensitizers for quasi-solid state dye sensitized ...solar cells. Polymer-sensitized solar cells (PSSC) fabricated utilizing PDPP-BBT and TDPP-BBT as the active layer resulted in a typical power conversion efficiency of 1.43% and 2.41%, respectively. The power conversion efficiency of PSSCs based on TDPP-BBT with use of TiCl4-modified TiO2 photoanode was about 3.06%, attributed to the reduced back recombination reaction and more charge carriers in the external circuit.
A novel dye D was synthesized and used as photosensitizer for quasi solid state dye-sensitized solar cells. A power conversion efficiency of 4.4% was obtained which was improved to 5.52% when ...diphenylphosphinic acid (DPPA) was added as coadsorbent.
Display omitted
► A new low band gap photosensitizer with cyanovinylene 4-nitrophenyl terminal units was synthesized. ► A power conversion efficiency of 4.4% was obtained for the dye-sensitized solar cell based on this photosensitizer. ► The power conversion efficiency of the dye-sensitized solar cell was further improved to 5.52% when diphenylphosphinic acid was added as coadsorbent.
A new low band gap photosensitizer, D, which contains 2,2′-(1,4-phenylene) bisthiophene central unit and cyanovinylene 4-nitrophenyl terminal units at both sides was synthesized. The two carboxyls attached to the 2,5-positions of the phenylene ring act as anchoring groups. Dye D was soluble in common organic solvents, showed long-wavelength absorption maximum at 620–636
nm and optical band gap of 1.72
eV. The electrochemical parameters, i.e. the highest occupied molecular orbital (HOMO) (−5.1
eV) and the lowest unoccupied molecular orbital (LUMO) (−3.3
eV) energy levels of D show that this dye is suitable as molecular sensitizer. The quasi solid state dye-sensitized solar cell (DSSC) based on D shows a short circuit current (
J
sc) of 9.95
mA/cm
2, an open circuit voltage (
V
oc) of 0.70
V, and a fill factor (FF) of 0.64 corresponding to an overall power conversion efficiency (PCE) of 4.40% under 100
mW/cm
2 irradiation. The overall PCE has been further improved to 5.52% when diphenylphosphinic acid (DPPA) coadsorbent is incorporated into the D solution. This increased PCE has been attributed to the enhancement in the electron lifetime and reduced recombination of injected electrons with the iodide ions present in the electrolyte with the use of DPPA as coadsorbant. The electrochemical impedance spectroscopy (EIS) results indicated that the augment ascribes to inhibited interfacial charge recombination between the conduction band electrons and the tri-iodide ions in the electrolyte.
PDF
