Power Conversion Efficiency Of Dye-sensitized Solar Cells Research Articles

Effects of Several Auxiliary Acceptors and Anchoring Groups on Charge Transfer and Photophysical Properties of D-A-π-A Type DSSCs: A DFT Study.

In this paper, we performed theoretical studies on the twelve D-A-π-A type organic dyes (G-1 ~ G-3, M-1 ~ M-3, J-1 ~ J-3, and S-1 ~ S-3) with 9-phenylcarbazole as the electron donor in anticipation of the application of these dyes in dye-sensitized solar cells (DSSCs). DFT and TD-DFT methods are applied to investigate in detail the molecular geometries, frontier molecular orbitals (FMOs), absorption spectra, charge density difference (CDD), and transition density matrix (TDM) of several dyes. The results show that the M-series (M-1 ~ M-3) dyes have the largest dihedral angles between the electron donor and the auxiliary acceptor and also has the largest energy gaps in HOMO-LUMO orbitals, which greatly reduces the charge transfer efficiency. Finally, the UV-Vis absorption spectra inferred that the anchoring groups modified with o-nitrobenzoic acid (G-3, M-3, J-3, S-3) can red-shift the absorption peaks of the dyes, which results in higher light-harvesting efficiency and improves the power conversion efficiency of DSSCs. Overall, all of these dyes contribute to the improvement of photovoltaic power conversion efficiency and have potential for application in DSSCs devices.

Experimental and computational investigation of multi-walled carbon nanotubes decorated by Co–Ni–Se@MoSe2 core–shell as a sustainable counter electrode for 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 (DSSCs). Herein, Co–Ni–Se@MoSe2 core–shell structures decorated on multi-walled carbon nanotubes (MWCNTs) were synthesized for the first time by the hydrothermal and probe-sonication methods. The electrochemical performance of this composite was examined using electrochemical measurement techniques. The results showed improved properties and better electrochemical activities of the Co–Ni–Se@MoSe2@MWCNTs than Pt and other counter electrodes (CEs) for the triiodide reduction and exhibit good electrochemical stability in iodine-based electrolytes. The power conversion efficiency of DSSCs based on Co–Ni–Se@MoSe2@MWCNTs CE reaches 9.43%, significantly superior to that with Co–Ni–Se@MoSe2 core–shell (8.13%), Pt CE (7.44%), and other CEs. The notable performance is attributed to the synergistic effect between Co–Ni–Se@MoSe2 and MWCNTs. As a result, the transfer of electrons to the active site is promoted, the agglomeration of Co–Ni–Se@MoSe2 is hampered, and more active sites are available. Density functional theory calculations revealed that I2 adsorption on MoSe2 surfaces facilitated the generation of I− ions, which played a critical role in enhancing the reaction efficiency. Therefore, the Co–Ni–Se@MoSe2@MWCNTs composite is a promising candidate for use in high-performance DSSCs.

Visible light photoredox catalysis for the synthesis of new chromophores as co-sensitizers with benchmark N719 for highly efficient DSSCs

Dye-sensitized solar cells (DSSCs) are becoming increasingly popular as low-cost organic photovoltaic devices due to their ease of fabrication and affordability. However, a primary limitation of DSSCs is their inability to absorb the entire solar spectrum, leading to lower efficiency. To overcome this limitation, a study was conducted to investigate the use of co-sensitization with two dyes that absorb different wavelengths of light to enhance the overall light absorption. In this study, four novel donor-acceptor (D-A) dyes (5a-d) containing benzo-1,4-diazine or benzo-1,4-oxazine groups as donors and a carbonyl group as an anchor were synthesized using a green and sustainable method to be used as co-sensitizers in DSSCs. These photosensitizers were co-sensitized with the Ru(II) dye N719 and were observed to significantly improve the light-harvesting ability of the device. The co-sensitizers (5a-d) reduced charge recombination, inhibiting dye aggregation, and increased dye loading on the TiO2 photoanode, leading to improve the overall device performance because of the appropriate molecular volume structures of (5a-d), which can fill the adsorption gap between N719 dye. The DSSC device of N719 showed a power conversion efficiency (PCE) of 7.81 % (JSC = 19.06 mA cm−2, VOC = 0.65 V, and FF = 61.24%). After co-sensitization, the PCE and short-circuit current of the device were significantly improved to reach (PCE = 8.79, JSC = 22.89 mA cm−2 and VOC = 0.68 V for 5a), (PCE = 8.56%, JSC = 22.37 mA cm−2, and VOC = 0.68 V mA cm−2 for 5b), (PCE = 8.59%, JSC = 22.45 mA cm−2, and VOC = 0.67 V for 5c) and (PCE = 8.50%, JSC = 21.93 mA cm−2, and VOC = 0.67 V for 5d). These findings demonstrate that co-sensitization with these novel dyes can compensate for the absorption defects of the Ru(II) dye and suppress charge recombination, leading to enhanced overall PCE in DSSCs.

Effect of small-size co-sensitizer on acid-base co-sensitization system of dye-sensitized solar cells

Inhibition of electron recombination and dye aggregation is a crucial strategy to enhance the power conversion efficiency (PCE) of co-sensitized solar cells. Here, large-size organic dyes TA, TP containing triphenylamine donor, cyanoacetic acid and pyridine acceptor are prepared. Different molar ratios are used to explore the optimal acid-base co-sensitization systems, different concentrations of small-size co-sensitizer (coded EA) are added to the optimal acid-base co-sensitization system non-competitive adsorption, and the effect of EA on acid-base co-sensitization system was studied. The results show that the addition of EA greatly improves the molar absorbance of dye molecules, and the introduction of oxyalkyl chains in the triphenylamine donor effectively inhibits the interfacial charge recombination and dye aggregation, so that the short-circuit current density (Jsc) of ternary co-sensitization system increased from 10.81 mA cm–2 to 13.70 mA cm–2. At the same time, PCE based on TA@TP(3:2)@EA(100%) devices improved by 30.61% (from 4.9% to 6.4%). The electron-rich EDOT of EA fills the adsorption gap of acid-base dye on the TiO2 surface, increases the overall dye load and photogenerated electron density, and thus increases the open-circuit voltage (Voc) and Jsc of the devices. This ternary co-sensitization provides more options for improving the PCE of dye-sensitized solar cells (DSSCs).

Performance Improvement of Dye-Sensitized Solar Cells with Pressed TiO2 Nanoparticles Layer

A simple and low-cost fabrication method of dye-sensitized solar cells (DSSCs) was developed to improve the structure and performance of the photoanode with the pressed layer and compact TiO2 thin film using spin coating, screen printing, and mechanical compression. In this study, four different TiO2 layers were adopted to fabricate photoanodes: a mesoporous TiO2 nanoparticles (NPs) layer, a pressed TiO2 NPs layer, a mesoporous TiO2 NPs layer on the TiO2 compact thin film, and a pressed TiO2 NPs layer on the TiO2 compact thin film. The compact thin film was deposited on the fluorine-doped tin oxide (FTO) glass via spin coating, while the mesoporous TiO2 NPs layer was deposited via the screen-printing method. The pressed TiO2 NPs layer was produced by compressing the mesoporous TiO2 NPs layer with a hydraulic press machine. When using the pressed TiO2 NPs layer for the photoanode of DSSC, the power conversion efficiency of DSSC was enhanced the most. The electron lifetime for DSSC with photoanodes based on the pressed TiO2 NPs and mesoporous TiO2 NPs layers were 8.217 and 6.287 ms, respectively. The power conversion efficiency of DSSC with photoanodes based on the pressed TiO2 NPs layer was 5.4%, while that based on the mesoporous TiO2 NPs layer was 4.08%. DSSC with photoanodes based on the pressed TiO2 NPs layer showed a significant increase in the power conversion efficiency by 36.16% compared to that based on the mesoporous TiO2 NPs layer.

Photon up-conversion in Er3+ ion-doped ZnO-Al2O3-BaO-B2O3 glass for enhancing the performance of dye-sensitized solar cells

One of the main limitations in the development of dye-sensitized solar cell (DSSC) is contributed by the optical losses that occur within the absorber layer due to spectral mismatch. DSSC typically only absorbs solar light within the visible region (i.e. up to 800 nm), while the photon energy in the infrared region remain unutilized. Here we report the integration of Er3+ ion-doped glass as up-conversion (UC) element in DSSC and study their effect on the photovoltaic performances. Several characterizations were conducted including physical, structural, optical, luminescence, and radiative properties on the glass sample, while current-voltage and incident photon-to-current conversion efficiency characterization were conducted to analyze the electrical properties of DSSC. The UC luminescence spectra of the glass sample under 800 nm excitation showed green light emissions that were located between 531 and 553 nm. The UC luminescence band of glass sample was confirmed suitable with the absorption band of Z907 dye. After placing the UC glass below the DSSC’s counter electrode side, the power conversion efficiency of DSSC were mostly positively affected by the presence of UC glass, where the highest improvement of around 7.21 % was obtained for DSSC coupled with 2.0 mol% of Er3+ ion-doped glass. The enhancement was primarily attributed to the improved light harvesting due to the UC mechanism within the device as indicated by the increase in external quantum efficiency and fill factor. Our contribution provides a simple yet versatile approach in improving DSSC performance via the application of a free standing Er3+ ion-doped up-conversion glass.

A Review of Transition Metal Sulfides as Counter Electrodes for Dye-Sensitized and Quantum Dot-Sensitized Solar Cells.

Third-generation solar cells, including dye-sensitized solar cells (DSSCs) and quantum dot-sensitized solar cells (QDSSCs), have been associated with low-cost material requirements, simple fabrication processes, and mechanical robustness. Hence, counter electrodes (CEs) are a critical component for the functionality of these solar cells. Although platinum (Pt)-based CEs have been dominant in CE fabrication, they are costly and have limited market availability. Therefore, it is important to find alternative materials to overcome these issues. Transition metal chalcogenides (TMCs) and transition metal dichalcogenides (TMDs) have demonstrated capabilities as a more cost-effective alternative to Pt materials. This advantage has been attributed to their strong electrocatalytic activity, excellent thermal stability, tunability of bandgap energies, and variable crystalline morphologies. In this study, a comprehensive review of the major components and working principles of the DSSC and QDSSC are presented. In developing CEs for DSSCs and QDSSCs, various TMS materials synthesized through several techniques are thoroughly reviewed. The performance efficiencies of DSSCs and QDSSCs resulting from TMS-based CEs are subjected to in-depth comparative analysis with Pt-based CEs. Thus, the power conversion efficiency (PCE), fill factor (FF), short circuit current density (Jsc) and open circuit voltage (Voc) are investigated. Based on this review, the PCEs for DSSCs and QDSSCs are found to range from 5.37 to 9.80% (I-/I3- redox couple electrolyte) and 1.62 to 6.70% (S-2/Sx- electrolyte). This review seeks to navigate the future direction of TMS-based CEs towards the performance efficiency improvement of DSSCs and QDSSCs in the most cost-effective and environmentally friendly manner.

Rapid synthesis of SrTiO3 nanocubes and replacement of the high-cost platinum electrode with SrTiO3@PANI nanocomposite in dye-sensitized solar cells

In this report, SrTiO3 was synthesized in a short time (10 min) as a perfect nano-cube shaped and high-quality crystal using microwave assisted method without any further annealing process. Moreover, SrTiO3 nanocubes were incorporated into the polyaniline (PANI) structure at different amounts and resulted nanocomposites were employed in dye sensitized solar cell (DSSC) as counter electrode (CE). Incorporation of SrTiO3 nanocubes led to enlargement of active surface area and increment in electrocatalytic activity of nanocomposites, resulting in lower electron transfer resistance and excellent charge transfer kinetics at the interfaces of CE/FTO and CE/electrolyte. As a result, photovoltaic (PV) parameters of DSSC improved with incorporation of SrTiO3 nanocubes compared to the bare PANI. Furthermore, 2 wt % SrTiO3 doped PANI nanocomposite (SP2) CE exhibited a better catalytic performance in comparison to the bare PANI and Pt CEs, resulting in higher power conversion efficiency (PCE). The PCE of the DSSC with SP2 CE was extracted as 7.57 %, while the PCEs of the cells employing bare PANI and conventional Pt CEs were calculated as 5.46 % and 7.16 %, respectively. By incorporation of SrTiO3 nanocubes, the PCE of DSSC with bare PANI is enhanced as 38.7 % due to the high redox nature of SrTiO3 and expanding of active surface area stem from nanocubes of SrTiO3. The obtained results suggest that SrTiO3 can be synthesised using simple microwave assisted method in a very short time and with high quality without any further annealing procedure. Furthermore, doping of 2 wt % SrTiO3 nanocubes into PANI can be alternative to the high-cost and rare Pt for commercialization of the DSSCs in near future.

Poly(3,4-ethylenedioxythiophene) decorated MXene as an alternative counter electrode for dye-sensitized solar cells

Counter electrodes (CE) layer in dye-sensitized solar cells (DSSCs) are possibly the most exorbitant material due to the presence of scarce earth metal, platinum (Pt). The prospective substitution of a Pt-CE would effectively pave the way for broad commercialization of the DSSC technology. In this regard, this work is focused on the fabrication of poly(3,4-ethylene dioxythiophene) decorated MXene (PEDOT@Ti3C2Tx) composite electrode, and its performance as a CE in DSSC was tested for the replacement of high-cost Pt-CE. The 2D-Ti3C2Tx was initially synthesized by the selective chemical etching method, followed by the electro-polymerization of 3,4-ethylenedioxythiophene (EDOT) monomer on the Ti3C2Tx surface. Further, X-ray diffraction (XRD), Raman, high-resolution scanning electron microscopy (HR-SEM), and X-ray photoelectron spectroscopy (XPS) characterization results confirm the successful formation of the PEDOT@Ti3C2Tx composite. PEDOT@Ti3C2Tx-CE display a strong electrocatalytic activity toward the iodide/triiodide electrolyte and good charge transfer kinetics with low charge transfer resistance close to the performance of the Pt electrode, as shown by electrochemical experiments. On the other hand, further testing of the device fabricated with thermally decomposed Pt-CE DSSCs achieved an efficiency of 8.7% under simulated 1SUN light at AM1.5G, whilst the DSSC built with the as-prepared composite material had 7.12% efficiency under the same conditions. PEDOT@Ti3C2Tx-CE composite DSSC outperformed PEDOT-CE and Ti3C2Tx-CE DSSC in power conversion efficiency improvements (PCE), demonstrating that PEDOT@Ti3C2Tx composite possesses a strong catalytic activity with noticeable charge transfer and mass transport capabilities. Therefore, the as-fabricated composite film takes utilization of the conductivity and electrocatalytic capabilities of the two components, increasing the overall power conversion efficiency of DSSC. The 15-days stability investigation demonstrates that the PEDOT@Ti3C2Tx-CE-based DSSC exhibits a consistent performance and corrosion resistant toward the iodide/triiodide redox electrolyte. Therefore, overall performance level of the PEDOT@Ti3C2Tx-CE thus entices more study for the replacement of Pt in DSSC and is indeed evinced to be a prospective noble metal electrode contender.

The improved performance of dye‐sensitized solar cells using co‐sensitization and polymer gel electrolyte

To investigate the photovoltaic capabilities as a sensitizer and co-sensitizer for dye-sensitized solar cells (DSSCs), a new metal-free organic dye (CDIB) was synthesized. In addition, different concentrations of 1-n-hexyl-3-methylimidazolium iodide ionic liquid (IL) doped poly(vinylidene fluoride-hexafluoropropylene) gel polymer electrolytes are prepared and the high conductive electrolyte is used to fabricate the devices. The device having CDIB sensitizer and IL-15% electrolyte showed an efficiency of 1.86%. Further, the effect of CDIB co-sensitization on Z907 is examined. Consequently, the power conversion efficiency of DSSC with co-sensitized dye is raised by 23.29%, from 4.55 to 5.61%, when compared to DSSCs with individual dyes. This improvement is mostly due to an increase in a short-circuit current density and open-circuit voltage. Highlights Co-sensitization is being used to enhance the performance of DSSCs. Poly(vinylidene fluoride-hexafluoropropylene)-based gel polymer electrolytes doped with different amounts of 1-n-hexyl-3-methylimidazolium iodide were prepared for improving the conductivity of electrolyte. A co-sensitized DSSC has an efficiency of 5.61%. With co-sensitization, both VOC and JSC increased significantly.

Photoelectric Performance Optimization of Dye-Sensitized Solar Cells Based on ZnO-TiO2 Composite Nanofibers

As the electron transport layer of dye-sensitized solar cells (DSSCs), the photoanode is an important component that affects photoelectric conversion efficiency (PCE). The commonly used material titanium dioxide (TiO2) is difficult to prepare as nanostructures with large specific surface area, which affects dye loading and electrolyte diffusion. Herein, TiO2 nanofibers and ZnO-TiO2 composite nanofibers with different molar ratios are synthesized by electrospinning technology. The above nanofibers are coated on photoanodes by the doctor blade method to assemble DSSCs. The influence of the composite ratio of ZnO-TiO2 composite nanofibers on the photoelectric performance of the assembled DSSCs is explored. The ZnO-TiO2 composite nanofibers with a molar ratio of 1 : 2 have large specific surface area and porosity and have the smallest charge transfer resistance at the photoanode-electrolyte interface. The PCE of the nanofiber-modified DSSCs reaches a maximum of 3.66%, which is 56% higher than that of the TiO2 nanofiber-modified DSSCs. The photovoltaic parameters such as open circuit voltage (VOC), current density (JSC), and fill factor (FF) are 0.58 V, 10.36 mA/cm2, and 0.61, respectively. Proper compounding of zinc oxide (ZnO) can not only make the nanofibers absorb more dyes and enhance the light-harvesting ability but also improve the diffusion of the electrolyte and enhance the electron transport, thus successfully improving the power conversion efficiency of DSSCs.

Improved performance of dye sensitized solar cell by exploration of photoanode and ruthenium based dye

We report two different fabrication methods (Doctors blade and Screen print) of photoanode and influence of three ruthenium based dyes (N3, N749 and Z907 and also their mixed dye) on dye sensitized solar cells (DSSCs). We found the increased effective surface area and lower densification in screen printed film. Rough surface of these films also improved adsorption of dyes to the photo anode film. On the other hand, mixed dye is an approach to harvest a wider range of solar lights on cells and exhibited peaks were found at 530 nm for N3 and 540 nm for Z907. Another peak at 620 nm was observed for N749 which revealed significant light absorption and photosensitization compared with the individual dye solutions. In this article, photovoltaic performances of DSSCs using these dyes and photoanodes were also evaluated and compared. The overall power conversion efficiencies of DSSCs lay in the range of 1.26–1.61%. Screen printed film with mixed dye showed the highest efficiency.

Fabrication of electrospun BaTiO3/chitosan/PVA nanofibers and application for dye-sensitized solar cells

Perovskite BaTiO3 nanoparticles were synthesized by a hydrothermal method. BaTiO3/chitosan (CS)/Polyvinyl alcohol (PVA) nanofibers with an average diameter of 265.3 ± 52 nm were fabricated via an electrospinning method. The nanofibers were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), and thermal analysis method (TGA). The photoanodes of dye-sensitized solar cells (DSSC) were fabricated based on the BaTiO3/CS/PVA nanofibers. The photovoltaic properties of the cells were calculated based on the current density – voltage curves. The maximum power conversion efficiency of DSSC with CS/PVA/BaTiO3 nanofibers was 0.49% with the natural dye sensitizer extracted from the leaf of the magenta plant.

Enhanced performance of dye-sensitized solar cells by co-sensitization of metal-complex and organic dye

We systematically investigated a co-sensitized dye comprising of the Ru-complex (N719) dye blended with organic (Coomassie brilliant-blue R-250) as a novel photosensitizer for application in dye-sensitized solar cells (DSSCs). Compared with DSSCs made with the individual dyes, the power conversion efficiency of DSSC with co-sensitized dye is increased by 22 %, i.e., from 9.07 to 11 %. This enhancement results mainly from the significant increase in the open-circuit voltage (VOC) upon co-sensitization due to the upward movement of the conduction band edge and reduction in the charge recombination. Impedance spectroscopy analysis reveals higher charge recombination resistance and greater carrier lifetime for the co-sensitized dye-based DSSC, suggesting that the suppressed recombination due to improved morphology and reduced defects yields a high VOC. Moreover, co-sensitized DSSC exhibited enhanced short circuit current (JSC) and fill factor (FF). This strategy of using a co-sensitized dye as a photosensitizer in DSSCs could pave an effective way to approach high-performance, cost-effective DSSCs.

Impact of coupled plasmonic effect with multishaped silver nanoparticles on efficiency of dye sensitized solar cells

Dye sensitized solar cells (DSSCs) have numerous advantages, but in order to use widespread industrial deployment we need to boost the power conversion efficiency. One promising approach to improve DSSC performance is to improve the spectral response of sensitizers with metal nanoparticle-based surface plasmon resonance. Even single shaped nanoparticles (NPs), however, have physical limitations. Thus, in this study a simple synthesis route is used to fabricate multishaped silver (Ag) NPs to create a coupled plasmonic effect in DSSC to cover more of the solar spectrum. The impact of multishaped AgNPs combinations are studied to determine which aspects improve the power conversion efficiency of DSSC. A detailed investigation was made of both the TiO2 (XRD) and AgNPs (UV–Vis spectrometry) to couple the impacts on the DSSC (I-V) with the combination of the morphologies (TEM and FESEM) of AgNPs. Synthesized AgNPs with distinct extinction cross section covers the visible and IR regime from 300 nm to 1100 nm by tuning its plasmonics band. It is inferred that multi-shaped AgNPs predominately enhance the light harvesting, charge separation and carrier transportation. The results show that the increment in short circuit current and open circuit voltage resulted in an increase of 45% overall power conversion efficiency in the standard DSSC device is attributed to the usage of multi-shaped AgNPs. Finally, a mechanism is proposed to support the outcome of the experiment by demonstrating the extinction cross section and the local field of the various shaped AgNPs using Finite-difference time-domain (FDTD) simulation.

A comprehensive review of dye-sensitized solar cell optimal fabrication conditions, natural dye selection, and application-based future perspectives.

Dye-sensitized solar cells (DSSC) constructed using natural dyes possess irreplaceable advantages in energy applications. The main reasons are its performance, environmentally benign dyes, impressible performance in low light, ecologically friendly energy production, and versatile solar product integration. Though DSSCs using natural dyes as sensitizers have many advantages, they suffer from poor efficiency compared to conventional silicon solar cells. Moreover, the difficulty in converting them to practical devices for the day-to-day energy needs has to be addressed. This review will outline the optimization of conditions to be followed for better efficiency in DSSCs using natural dyes as sensitizers. This review has taken into account the importance of the first step towards the fabrication of DSSC, i.e. the selection process. The selection of plant parts has a noticeable impact on the overall efficiency of the device. Accordingly, a proper study has been done to analyse the plant's parts that have shown better results in terms of device efficiency. In addition to this, a wide range of techniques and factors such as extraction methods, the solvent used, coating techniques, immersing time, and co-sensitization have been taken into consideration from the studies done over the period of 10years to examine their influence on the overall performance of the DSSC device. These results have been addressed to stipulate the best suitable condition that will help supplement the efficiency of the device even further. Also, the future perspectives, such as the DSSCs use inwearable devices, incorporating various approaches to enhance the power conversion efficiency of DSSCs using natural dyes, andthermochromism ability for DSSCshave been discussed.

Hybrid titanium dioxide/sericite light scattering layer to enhance light harvesting of dye-sensitized solar cells

Intensification of light harvesting is an imperative strategy to improve the photovoltaic performance of dye-sensitized solar cells (DSSCs). The typical way is to employ a light scattering layer on top of the photoanode to augment the photon scattering of incident light for light harvesting of dye sensitizers. In this study, we have designed a new light scattering layer consisting of micro-sized sericite flakes and TiO2 nanoparticles, and material optimization is performed by using two sizes of TiO2 nanoparticles (P25-TiO2 of 20-30 nm and B-TiO2 of 30-100 nm) as the matrix to dope sericite flakes. This hybrid scattering layer gives rise to an enhancement of power conversion efficiency of DSSC under 1 sun and low-intensity illuminations. Maximum cell efficiencies of 8.667 % and 8.963 % are recorded for the DSSCs employing P25-TiO2/5 wt% sericite and B-TiO2/25 wt% sericite scattering layer, respectively, at 1 sun illumination, which outperforms that employing pure TiO2 scattering layer (8.2 %). Maximum cell efficiencies of 22.936 % and 23.121 % are optimized at 6,000 lux following the same TiO2/sericite hybrid systems. Such addition of sericite in the scattering layer indeed enhances the light harvesting performance and offers a new pathway to prepare more efficient light scattering layer.

Plasmonic dye-sensitized solar cells through collapsible gold nanofingers

Plasmonic nanostructures are successfully demonstrated in solar cells due to their broad spectra-selective resonance in the range of ultraviolet to near-infrared, and thus light absorption can be mostly improved and power conversion efficiency (PCE) further. Here, we demonstrate plasmonic dye-sensitized solar cells (DSSCs) using collapsible Au nanofingers to build photoanode to enhance light absorption. In this plasmonic DSSCs, by balancing local field enhancement due to gap-plasmon resonance and dye fluorescence quenching, the optimal gap size in collapsed Au/Al2O3/Au nanofingers is designed by twice the Al2O3 thickness and then deposited a TiO2 layer as photoanode. The results show that the PCE of DSSCs is mostly improved as compared to DSSCs with photoanode of Au/Al2O3/TiO2 films, which can be ascribed to the coupled local field enhancement within the sub-nanometer gaps. In addition, fluorescence of dyes on plasmonic nanofingers is nearly 10 times higher than plain Au/Al2O3/TiO2 films, which further proves the dye absorption enhancement. These plasmonic nanofingers enable the precise engineering of gap-plasmon modes and can be scaled up to wafer scale with low cost by the nanoimprint lithography technique, which suggests the feasibility of applying our result in constructing the photoanode for other types of solar cells.

Natural rubber (Hevea Brasiliensis)-based quasi-solid electrolyte as a potential candidate for arresting recombination and improving performance in aqueous dye-sensitized solar cells

We successfully fabricated dye sensitized solar cells (DSSCs) employing a quasi-solid state electrolyte based on pristine insulator natural rubber latex from Hevea brasiliensis and iodide electrolyte. Optimized devices exhibited a maximum power conversion efficiency (PCE) of 1.14% under simulated sunlight with 90 mW/cm2 illumination, 0.46% under 100 mW/cm2 and 7.85% under low intensity illumination of 1000 lx (Daylight LED). This gives a new perspective for the introduction of natural rubber latex abundant in nature as an additive to the water based redox mediator in order to improve the PCE in DSSC. A detailed study on the interfacial charge transfer in fabricated devices revealed that the introduction of rubber helped in arresting the back electron transfer, which was predominant in aqueous electrolyte based dye sensitized solar cell. This opens up opportunities for water-based electrolyte based on natural raw materials to be used in nature inspired DSSC technology.

Low-Temperature Chemical Sintering Technique for Flexible Dye-Sensitized Solar Cells

Chemically sintered, mesoporous TiO2 electrodes were prepared at low-temperature (≤150 °C) using polymeric- binder free TiO2 paste consisting of binary-liquid mixture of 1-octanol and a series of chlorinated hydrocarbons (CHCs), such as carbon tetrachloride (CCl4), tetrachloroethylene (C2Cl4) or chloroform (CHCl3). In this work, CHCs were introduced to lower the boiling point of the mixture and to perform as an active agent for chemical treatment of TiO2 paste. Long chain alcohol 1-octanol increased the viscosity and diminished the surface tension of TiO2 paste to the hydrophobic surface of the substrate, which promoted the paste adhesion. A maximum power conversion efficiencies (PCEs) of c.a. 6.66 and 4.30% (under 1 sun illumination –100 mW cm-2) were obtained for the rigid dye-sensitized solar cells (DSSCs) with fluorine-doped tin oxide (FTO) and the flexible one with indium tin oxide-polyethylene naphthalate (ITO/PEN) substrates, respectively. Under LED daylight illumination, maximum PCEs of 10.10% at 3.39 mW cm-2 and 8.35% at 1.87 mW cm-2 have also achieved for DSSCs prepared on FTO substrate. The improved chemical bonding of particle network and strong adhesion to the substrates facilitated the electron transfer from TiO2 photoelectrodes to charge collectors, which played an important role for the significant enhancement of photocurrent density as well as PCE of DSSCs. The effect of CHCs on TiO2 is found to be a promising strategy to prepare well-connected TiO2 film for other applications.