Flexible Dye-sensitized Solar Cells Research Articles

Full-stainless steel mesh dye-sensitized solar cells based on core-shell ZnO/TiO2 nanorods

We report fabrication and photovoltaic properties of flexible dye-sensitized solar cells (FDSSCs) based on stainless steel mesh (SSM)-supported core-shell ZnO/TiO2 nanorods photoanode and Pt nanoparticles- coated SSM counter electrode (Pt/SSM CE). The core-shell ZnO/TiO2 structures were prepared via simple chemical bath deposition, and optimal conversion efficiency of 2.84% was achieved. When aluminum foil membrane was introduced on the back of the FDSSCs as reflecting film (Rf) for improving utilization of sunlight, the conversion efficiency of FDSSCs was increased from 2.84% to 3.12%. The relative improvement of 218% was achieved in conversion efficiency compared with similar device without TiO2 buffer layer and reflecting film (0.98%). Meanwhile, the Pt CE based on SSM possessed of higher catalytic ability and longer stability compared with ITO/PET-based Pt CE.

Flexible Dye-sensitized Solar Cell Using Titanium Gel at Low Temperature

Flexible dye-sensitized solar cells using binder free TiO2 paste for low temperature sintering are developed. In this paste a small amount of titanium gel is added to a paste of TiO2 nanoparticle. Analysis of titanium gel paste prepared at 150 °C shows that it has a pure anatase phase in XRD and mesoporous structure in SEM. The formation of the titanium gel 1- 2 nm coated layer is confirmed by comparing the TEM image analysis of the titanium gel paste and the pristine paste. This coating layer improves the excited electron transfer and electrical contact between particles. The J-V curves of the organic binder DSSCs fabricated at 150 °C shows a current density of 0.12 mA/cm2 and an open-circuit voltage of 0.47 V, while the titanium gel DSSCs improves electrical characteristics to 5.04 mA/cm2 and 0.74 V. As a result, the photoelectric conversion efficiency of the organic binder DSSC prepared at low temperature is as low as 0.02 %, but the titanium gel paste DSSCs has a measured effciency of 2.76%.

Optimizing room temperature binder free TiO2 paste for high efficiency flexible polymer dye sensitized solar cells

Binder free TiO2 paste is prepared using tert-butyl alcohol in dilute acidic conditions at room temperature for flexible polymer dye sensitized solar cells (DSSCs). The present paper reports the detailed studies carried out to elucidate the importance of stirring times during the paste preparation on the final device performance. The maximum conversion efficiency of 4.2% was obtained for flexible DSSCs fabricated on tin doped indium oxide/polyethylene naphthalate substrates using TiO2 paste prepared with an optimum stirring time of 8 h. The effect of optimum stirring times on the device characteristics has been understood in terms of the detailed morphology and surface area measurements.

Laser Sintering of TiO2 Films for Flexible Dye-Sensitized Solar Cells

In this study, laser sintering of TiO2 nanoparticle films on plastic substrates was conducted in order to improve the incident photon-to-electron conversion efficiency (IPCE) of flexible dye-sensitized solar cells (DSCs). Lasers with different wavelengths (355 nm and 1064 nm) were used to process the TiO2 electrodes. With an optimized processing parameter combination, the 1064 nm laser can sinter 13 μm thick TiO2 films uniformly, but the uniform sintering cannot be achieved by the 355nm ultraviolet (UV) laser, since the films possess a high absorption ratio at 355 nm. The experimental results demonstrate that the near-infrared laser sintering can enhance the electrical connection between TiO2 nanoparticles without destroying the flexible plastic substrate, reduce the transmission impedance of electrons and increase the absorption rate of incident light. Furthermore, the charge collection efficiency, fill factor, and short-circuit current have all been improved to some extent, and the solar conversion efficiency increased from 4.6% to 5.7%, with an efficiency enhancement reaching 23.9%.

Photoelectrochromic smart windows powered by flexible dye-sensitized solar cell using CuS mesh as counter electrode

Here we present a highly flexible indium tin oxide (ITO) and Pt-free dye-sensitized solar cell (DSSC) based on TiO2 nanotube arrays on Ti foil (TNARs/Ti) as the photoanode, CuS mesh transparent films (CMTFs) as the counter electrodes (CEs). These CMTFs not only exhibit superior transmittance and low resistance (a sheet resistance of 0.5 Ω sq−1 at ∼80% transmittance), but also demonstrate remarkable mechanical properties after bending test and high catalytic activity towards I−/I3− redox in DSSCs. What is more, a novel photoelectrochromic smart window (PECSW) with large color range is successfully fabricated and its transmittance can be automatically adjusted by the CMTF based DSSCs according to the intensity of sunlight.

Titanium mesh-supported “TiO2 nanowire arrays/Yb-Er-F tri-doped TiO2 up-conversion nanoparticles” composite structure: Designation for high efficient flexible dye-sensitized solar cells

Titanium (Ti) mesh-supported “TiO2 nanowire arrays (TNWAs)/Yb-Er-F tri-doped TiO2 up-conversion nanoparticles (YEF-TiO2-UCNPs)” composite structures were prepared as photoanodes of the flexible dye-sensitized solar cells (DSSCs) by using hydrothermal and spin-coating approaches. The as-synthesized YEF-TiO2-UCNPs which could enhance the absorption of N719 dyes by converting the near-infrared light to visible light exhibited better up-conversion luminescence properties than the YbEr co-doped TiO2 up-conversion nanoparticles (YE-TiO2-UCNPs). Moreover, the appropriate YEF-TiO2-UCNPs could enlarge light harvesting range of the formed flexible photoanode and improved the photovoltaic performance of the DSSCs. Under the simulated solar irradiation of 100 mW cm−2 (AM 1.5G), the flexible DSSC with a Ti mesh-supported “TNWAs/YEF-TiO2-UCNPs60%P2540%” composite structure achieved a short-circuit current density (Jsc) of 12.81 mA cm−2 and a power conversion efficiency (PCE) of 5.54%, showing improvements of 45.7% and 37.8% as compared with TNWAs/P25100% (8.79 mA cm−2, 4.02%), respectively.

Cobalt-Based Electrolytes for Efficient Flexible Dye-Sensitized Solar Cells

AbstractWe have developed new flexible dye-sensitized solar cells (DSSCs) comprising organic dye (JH-1), cobalt redox electrolyte and hierarchically structured TiO2 (HS-TiO2) photoelectrode prepared using an electrostatic spray method. The performance of JH-1 sensitized flexible DSSC with a cobalt redox electrolyte was compared with those of N719-based DSSC and DSSC with I-/ I3- redox electrolyte. As a result, JH-1 sensitized flexible DSSC with [Co(Ⅲ/Ⅱ)(bpy-pz)3](PF6)3/2 redox system exhibited a high photocurrent density of 9.17 mA cm-2, an open circuit voltage of 0.953 V, a fill factor of 0.70, and a power conversion efficiency of 6.12% under 1 sun illumination (100 mW cm-2). The incident photon-to-current conversion efficiency was measured to explain the photocurrent generation difference by different dyes and electrolytes. The electron recombination lifetime of cells was measured by intensity-modulated photovoltage spectroscopy. Mass transport in DSSCs employing cobalt redox electrolytes was also investigated by the photocurrent transient measurements and electrochemical impedance spectroscopy (EIS) analysis.

High performance flexible dye-sensitized solar cells base on multiple functional optimizations

A DSSCs photoanode structure of hierarchical coronary TiO2 nanorod arrays (HCTNAs) is constructed through a mild and controllable hydrothermal strategy. The two-step hydrothermal has been adopt to grow HCTNAs on the flexible ITO/PET conductive substrate directly. Interestingly, this kind of HCTNAs is constituted by unique top nano-bouquet and bottom nano-flower shrubs which modified nanorods. The unique structure is propitious to adsorb more dye molecules and scatter more photons on the basis of fast electron transport capacity. HCTNAs photoanodes are assembled into DSSCs, and get a gratifying photoelectric conversion efficiency. The power conversion efficiency (PCE) of the HCTNAs DSSCs is 62% increase compare to those of constructed by first step bare TiO2 nanorod arrays in the conversion efficiency. It is worth mentioning that our fabrication technology can convert bare TiO2 nanorod (1D) to nano-flower which with coronary (3D) TiO2 directly which on the flexible substrate. This is a significant technological breakthrough for the flexible photoanode substrate of dye-sensitized solar cells.

Characteristics of transparent indium zinc oxide electrode prepared on poly(ethylene naphthalate) by radio frequency magnetron sputtering for flexible dye-sensitized solar cells

In this study, for the use as a transparent electrode in flexible dye-sensitized solar cells (DSSCs), the indium zinc oxide (IZO) thin films on unheated poly(ethylene naphthalate) (PEN) substrate in pure argon ambient by radio frequency (RF) magnetron sputtering method have been prepared, and their characteristics with respect to RF power were investigated. It has been found that the IZO films on PEN show a dense amorphous structure and the surface microstructure of the films is hardly sensitive to the RF power. The electrical and optical properties of RF magnetron sputtered IZO thin films on PEN are strongly influenced by RF power. At a RF power of 60 W, it is obtained the IZO thin film with the sheet resistance of about 7.65 Ω/sq. and optical transmittance of about 80% at 550 nm wavelength, resulting in the highest value for figure of merit. The flexible DSSC device embedded with the transparent IZO electrode deposited at 60 W shows the high power conversion efficiency, which is the value of 4.7% under simulated air mass 1.5 irradiation.

Enhanced Photoelectrochemical Performances in Flexible Mesoscopic Solar Cells: An Effective Light‐Scattering Material

AbstractThe development of a suitable material with both effective light scattering and high surface adhesion properties that would allow a low‐temperature fabrication of a mechanically stable light trapping layer is critical for today's flexible plastic dye‐sensitized solar cells (DSCs) to reach comparable high power conversion efficiency (PEC) towards commercialization. In the present work, submicron‐sized titania particles of intensive surface roughness were strategically synthesized using a combined sol–gel and thermolysis approach. When used as a light‐trapping layer in flexible DSCs, the ideal strong light scattering ability of such materials enabled significant enhancement of light harvesting and thus greatly contributed to the photocurrent performances. This led to a nearly 30 % PEC improvement when compared to the flexible DSCs using nanoparticle‐based photoanodes of a similar film thickness.

A Smart Flexible Solid State Photovoltaic Device with Interfacial Cooling Recovery Feature through Thermoreversible Polymer Gel Electrolyte.

Quasi-solid-state dye-sensitized solar cells (DSSCs) fabricated with lightweight flexible substrates have a great potential in wearable electronic devices for in situ powering. However, the poor lifespan of these DSSCs limits their practical application. Strong mechanical stresses involved in practical applications cause breakage of the electrode/electrolyte interface in the DSSCs greatly affecting their performance and lifetime. Here, a mechanically robust, low-cost, long-lasting, and environment-friendly quasi-solid-state DSSC using a smart thermoreversible water-based polymer gel electrolyte with self-healing characteristics at a low temperature (below 0 °C) is demonstrated. When the performance of the flexible DSSC is hindered by strong mechanical stresses (i.e., from multiple bending/twisting/shrinking actions), a simple cooling treatment can regenerate the electrode/electrolyte interface and recover the performance close to the initial level. A performance recovery as high as 94% is proven possible even after 300 cycles of 90° bending. To the best of our knowledge, this is the first aqueous DSSC device with self-healing behavior, using a smart thermoreversible polymer gel electrolyte, which provides a new perspective in flexible wearable solid-state photovoltaic devices.

Effective Light Scattering Building Block for Enhanced Photoelectrochemical Performances of Flexible Solar Cells

Solar cells fabricated on flexible plastic substrates possess great potential towards commercialization standing on their light-weight, low-cost, low-tech fabrication, and flexibility to tolerant different outdoor/indoor application requirements. A lack of a suitable material with both effective light scattering and high surface adhesion properties that would allow the development of a mechanically stable light trapping top-coating layer through a low temperature process prevents today’s flexible plastic dye-sensitized solar cells (DSCs) to reach comparable high power conversion efficiency (PEC) towards commercialization. In the present work, submicron sized titania particles with intensive surface roughness were strategically synthesized using a combined sol-gel and thermolysis approach. When used as a light trapping layer in flexible DSCs, the ideal strong light scattering ability of such materials enabled dramatic enhancements on light harvesting and thus greatly contributed to the photocurrent performances. This led to a nearly 30% PEC enhancement when compared to the flexible DSCs using photoanodes made of nanoparticles with a similar film thickness.

Direct Comparison of Electron Transport and Recombination Behaviors of Dye-Sensitized Solar Cells Prepared Using Different Sintering Processes

Flexible dye-sensitized solar cells on plastic substrates have achieved a conversion efficiency of 8.6% with the hot compression technique (<150 °C). However, the value of efficiency is only 70% of that achieved using glass substrates with high-temperature sintering technique (500 °C). Investigating the origin of this difference is a critical step for further improving the performance of plastic dye-sensitized solar cells. In this study, an optimized ternary viscous titania paste without the addition of organic binders enables the fabrication of efficient dye-sensitized solar cells with a low-temperature process. Therefore, the electron-transport behavior of dye-sensitized solar cells can be directly compared with those prepared with the high-temperature sintering technique. In addition to the structural and optical differences, the hot compressed photoanode of dye-sensitized solar cells have an electron diffusion coefficient that is 2 times smaller and a recombination time that is 6 times shorter than th...

Scale-Up of the Electrodeposition of ZnO/Eosin Y Hybrid Thin Films for the Fabrication of Flexible Dye-Sensitized Solar Cell Modules.

The low-temperature fabrication of flexible ZnO photo-anodes for dye-sensitized solar cells (DSSCs) by templated electrochemical deposition of films was performed in an enlarged and technical simplified deposition setup to demonstrate the feasibility of the scale-up of the deposition process. After extraction of eosin Y (EY) from the initially deposited ZnO/EY hybrid films, mesoporous ZnO films with an area of about 40 cm2 were reproducibly obtained on fluorine doped tin oxide (FTO)-glass as well as flexible indium tin oxide (ITO)–polyethylenterephthalate (PET) substrates. With a film thickness of up to 9 µm and a high specific surface area of up to about 77 m2·cm−3 the ZnO films on the flexible substrates show suitable properties for DSSCs. Operative flexible DSSC modules proved the suitability of the ZnO films for use as DSSC photo-anodes. Under a low light intensity of about 0.007 sun these modules achieved decent performance parameters with conversion efficiencies of up to 2.58%. With rising light intensity the performance parameters deteriorated, leading to conversion efficiencies below 1% at light intensities above 0.5 sun. The poor performance of the modules under high light intensities can be attributed to their high series resistances.

Novel Design for Flexible Quasi-solid-state Dye-sensitized Solar Cells Based on Heat-resistant Glass Paper

Paper-based electronics have obtained increasing attention as they offer benefits of light weight, flexibility and low cost. In this work, heat-resistant borosilicate glass paper, showing extraordinary flexibility and being able to be treated at high temperature (~500 °C), is used as the substrate for flexible dye-sensitized solar cells (DSSCs) for the first time. High-quality photoanodes were prepared via a novel sequent filling method with the aid of poly(methyl methacrylate) PMMA and ice layers, leading to smooth and continuous TiO2 film. A complete different device structure design compared to the conventional one was also brought about, by taking advantage of using this photoanode as solid-state electrolyte supporter and being further connected with the counter-electrode. The prototype solar cell was successfully demonstrated for the first time, with a decent initiating photovoltaic performance, resulting in an efficiency of 0.85% (open-circuit voltage, Voc=0.67 V; short-circuit current density, Jsc=...

In situ growth of zinc oxide nanoribbons within the interstices of a zinc stannate nanoplates network on compacted woven metal wires and their enhanced solar energy application

A novel hybrid film is designed and prepared by in situ growth of ZnO nanoribbons in the interstices of Zn2SnO4 nanoplates network on the compacted woven metal wires through a simple process. The ZnO nanoribbons present in the ZnO/Zn2SnO4 composite film can enhance light harvesting, accelerate electron transport and induce a negative shift in the flat-band potential. Benefiting from its advantageous structure and composition, the ZnO/Zn2SnO4 film can be applied in many fields. For the flexible dye-sensitized solar cells (FDSSCs) employing optimized ZnO/Zn2SnO4 as a photoanode, the conversion efficiency reaches 2.41% corresponding to ∼36.2% improvement relative to the Zn2SnO4 nanoplates-based FDSSCs. Moreover, ZnO/Zn2SnO4-based FDSSC shows relatively good mechanical stability and long-term stability, retaining 95.1% and 93.3% of its initial efficiency after ten consecutive bending tests and after 15 days under sunlight, respectively; Additionally, the immobilized ZnO/Zn2SnO4 on the metal wires exhibits 96.8% photocatalytic degradation efficiency against an organic dye under UV light, and the photocatalytic performance can be restored almost completely by a simple chemical treatment. More importantly, the in situ growth technique demonstrated in this work can be adopted to fabricate other composite oxides on flexible substrates with high curvature surfaces for additional practical applications in flexible devices.

Controllable and large-scale fabrication of rectangular CuS network films for indium tin oxide-and Pt-free flexible dye-sensitized solar cells

Here we present a highly flexible and large-area CuS transparent conductive film (TCF) fabricated by colloidal crackle pattern as a counter electrode (CE) for flexible dye sensitized solar cell (DSSC). This rectangular CuS TCF can be fabricated on arbitrary flexible substrates at low temperature and exhibits superior mechanical robustness in bending cycling measurement. The transmittance and conductivity can be accurately controlled by controlling the sizes and shapes of the crackle patterns, ~ 90% transmittance can be achieved when the sheet resistances (Rs) are ~ 60Ω sq−1. Moreover, such CuS TCF has strong receivable ability of pH (1−13) and temperature changes (0–100°C). In the application of DSSC as CE, the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analyses of the CuS networks exhibit a comparable electrocatalytic behavior with the platinum (Pt) networks on polyethylene terephthalate (PET), yielding a power conversion efficiency (PCE) of 4.54% for DSSC based on CuS networks as CE and retaining > 90% PCE after 500 bending cycles. Such CuS TCF with high transparency, flexibility, conductivity and electrochemical catalytic ability shows great potentials in other wearable, light-weight electrochemical cells.

High Voltage Flexible ZnO Solar Cells Employing Bulky Organic Dye and [Co(bpy)3]2+/3+ Redox Electrolyte

We present fabrication and characterization of flexible high voltage dye-sensitized solar cells (DSSCs) by screen printing of porous ZnO photoelectrode to power up IoT (Internet of Things) nodes to substitute batteries. Combination of triphenylamine based organic dye, D35, and [Co(bpy)3]2+/3+ (bpy = 2,2’-bipyridine) redox electrolyte achieved high voltages approaching 1 V, owing to strong rectification of charge transfer processes by passivation of the ZnO surface by the adsorbed D35 layer. The system, however, suffered from limited diffusion of the Co complex redox couple within the porous photoelectrode, causing saturation of photocurrent and poor fill factor to limit the overall conversion efficiencies under high light illumination. The current/voltage linearity was improved by optimizing the thickness of porous ZnO layer and by use of low viscosity electrolyte solvent. The highest conversion efficiencies we obtained were 3.73 and 2.63% for the cells employing F-doped SnO2 (FTO) coated glass and indium tin oxide (ITO) coated poly-ethylenenaphthalate (PEN) film substrates, respectively.

Screen Printed Dye-Sensitized Solar Cells (DSSCs) on Woven Polyester Cotton Fabric for Wearable Energy Harvesting Applications

Recently, the demand for lightweight, flexible and wearable dye-sensitized solar cells has been increased rapidly. One driver for this is to meet the challenge of supplying power in e-textiles applications. Integrating this functionality in the textile will result in an improved feel of the fabric compared to the current approach of the integration of conventional plastic solar patches. A low temperature processed TiO2 paste was used in this work to develop a fabrication method based on screen printing and spray coating to obtain photovoltaic textiles. The fabrication method used is low temperature and is compatible with Kapton and standard woven 65/35 polyester cotton fabrics. Comparing to the latest literatures, [1–3] our results show an improved PV efficiency of 7.03% and 2.78% on Kapton and fabric respectively when using a platinum coated fluorine tin oxide (FTO) glass as the top electrode.

Preparation of Flexible Dye-sensitized Solar Cells Based on Hierarchical Structure ZnO Nanosheets

Preparation of Flexible Dye-sensitized Solar Cells Based on Hierarchical Structure ZnO Nanosheets