Flexible Dye-sensitized Solar Cells Research Articles

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

Growth of hierarchical TiO2flower-like microspheres/oriented nanosheet arrays on a titanium mesh for flexible dye-sensitized solar cells

A triple-layer TiO2(TiO2-TL) structure was synthesized with an over-layer composed of TiO2flower-like microspheres (MSs), a middle layer of nanosheet arrays (NSAs) and an under-layer of compact film (CF) on a titanium (Ti) mesh substrate using a one-step hydrothermal route and used to make a series of flexible dye-sensitized solar cells (DSSCs).

Development of Flexible Dye-sensitized Solar Cell Based on Pre-dyed Zinc Oxide Nanoparticle

Development of Flexible Dye-sensitized Solar Cell Based on Pre-dyed Zinc Oxide Nanoparticle

The preparation of highly flexible mesoporous TiC/CNF film for flexible dye-sensitized solar cells

The flexible TiC/carbon nanofiber (TiC/C NF) film was prepared by electrospinning, stabilization, and carbonization. All the obtained TiC/CNFs had rough surface and random orientation, and the TiC nanoparticles (NPs) were uniformly dispersed on the CNFs. With the increase of TiC NPs, the flexural property of TiC/CNF film increased. While, the electrical conductivity increased, reaching a largest value before decreasing as the amount of TiC NPs increases. These highly flexible films showed promising electrical conductivity and electrocatalytic activity. Hence, they were employed as counter electrodes (CEs) for flexible dye-sensitized solar cells (FDSSCs). After the optimization of the amount of TiC NPs in CNFs (when the Tip content in precursor was 12 wt%), a high conversion efficiency of 3.80% was obtained. This is due to its optimum electrical conductivity and catalytic active sites. Based on the optimum amount of TiC NPs, the mesopores TiC/CNF composite films were fabricated by the introduction of various amount of polymethyl methacrylate (PMMA) in an electrospun solution. With the ratio of PMMA/(PAN/PVP) increasing, the specific surface area and the electrical conductivity increased, reached the largest values corresponding to 1:1, and then decreased. The increased surface area and conductivity facilitated the diffusion of electrolyte and reduction of triiodide, resulting in the improvement of the properties of CEs. When the FDSSCs were assembled with mesoporous TiC/CNF films as CEs, the conversion efficiency can be further enhanced up to 4.47%, which can be even comparable to the Pt/FTO CE.

A novel bilayer photoanode made of carbon nanotubes incorporated TiO2 nanorods and Mg2 + doped TiO2 nanorods for flexible dye-sensitized solar cells

TiO2 nanorods (NRs), Mg2+ doped TiO2 (Mg2+/TiO2) NRs, and carbon nanotubes incorporated TiO2 (CNTs/TiO2) NRs are fabricated from the corresponding electrospun nanofibers (NFs) by ultrasonic treatment, respectively. Then these NRs are made into various photoanodic films through electrospray deposition and hot-compression for flexible dye-sensitized solar cells (FDSSCs). The conversion efficiency of FDSSCs is improved with the CNTs incorporation or the Mg2+ ions doping of TiO2. To further improve the properties of FDSSCs, various bilayer photoanodic films made of the smaller diameter NRs as under-layer and the larger diameter NRs as over-layer are prepared. Finally, a highest conversion efficiency of 3.9% is obtained using the bilayer NRs film composed of the smaller diameter CNTs/TiO2 NRs and the larger diameter Mg2+/TiO2 NRs. This efficiency is much higher than that of the single-layer NRs film based FDSSCs. This may be attributed to the increased light harvesting resulting from the scattering layer of the larger diameter NRs and the faster electron transport due to the two-level energy steps of the bilayer NRs film.

Using a low temperature method to fabrication of flexible dye sensitized solar cells with three different counter electrodes

In this experimental work, we fabricated a flexible dye-sensitized solar cell with different counter electrodes. An electrophoresis method was served to deposition of TiO2 on the ITO-coated poly(ethylene terephthalate) (ITO–PET) as a flexible substrate. Also, a low-temperature process was used to sintering TiO2 particles. Three different counter electrodes namely Pt, multi-walled carbon nanotube and graphene were utilized in the flexible dye-sensitized solar cell. Cross section scanning electron microscopy (SEM) images were used to obtain the TiO2 film Thickness. Also, the surface morphology of the TiO2 and also Pt films were obtained by SEM images. The crystallinity of the prepared films was investigated by X-ray diffraction pattern. The optical properties of the TiO2 film were studied by diffuse reflectance spectroscopy. The flexible dye-sensitized solar cell was made by TiO2 film deposited on the flexible ITO–PET substrate, different counter electrodes, I3 −/I− electrolyte and surlyn as a sealer. The solar cell performance was investigated by short circuit current density–open circuit voltage curves. It was found that the fabricated flexible dye-sensitized solar cells had a good efficiency compared with rigid solar cells. Also, it was concluded that the solar cell made from Pt as counter electrode showed the best performance that is mainly due to the high catalytic activity of Pt respect to the other counter electrodes.

Flexible woven metal wires supported nanosheets and nanoparticles double-layered nitrogen-doped zinc stannate toward enhanced solar energy utilization

For enhanced solar energy application, double-layered nitrogen-doped Zn2SnO4 film consisting of bottom nanosheets and top nanoparticles is designed and synthesized on flexible woven metal wires. The effects of doping concentration of nitrogen element (N) and the amount of coating nanoparticles on electronic, optical properties and stability are investigated in detail by various testing techniques. The results show that in the double-layered structure, the nanosheets array can provide direct transport pathways for photoinduced electrons, while the nanoparticles can provide high surface area. On the other hand, doped N element is conducive not only to the absorption of visible light due to narrowed band gap, but also to suppression of charge recombination. With the optimized double-layered N-doped Zn2SnO4 as photoanodes of flexible dye-sensitized solar cells, the corresponding photoelectric conversion efficiency is 2.302% compared to 1.332% and 1.826% in case of pure Zn2SnO4 nanosheets and N-doped Zn2SnO4 nanosheets; The double-layered N-doped Zn2SnO4 is also determined to be high-performance immobilized photocatalyst with a better recyclability for the photodegradation of organic pollutant under sunlight irradiation; More importantly, the preparation methods is also applicable to fabricate other composite oxides on wire-shaped substrate for more practical applications in flexible devices.

Co-sensitization of metal free organic dyes in flexible dye sensitized solar cells

Abstract A metal-free organic dye (JH-1) and an unsymmetrical squaraine dye (SQ2) were used for co-sensitization of a flexible TiO2 electrode in order to obtain a broad spectral response in the visible light regions. Because of enhanced light absorption, the performance of the flexible plastic dye-sensitized solar cells (DSSCs) was enhanced. The dye concentration of co-sensitized TiO2 film was higher than that of individual dye-sensitized TiO2 film, leading to improved photovoltaic performance with the panchromatic light harvesting of JH-1 and SQ2 (350–720 nm). Optimum molar ratio of individual dye, dye concentration and adsorption kinetics onto the TiO2 photoelectrode, and ideal thickness of HS-TiO2 layer have been investigated. A flexible DSSC co-sensitized with the molar ratio of 60:40 (JH-1:SQ2) and TiO2 film thickness of 6 μm yielded a high photocurrent density of 12.32 mA cm−2, an open circuit voltage of 0.754 V, a fill factor of 0.68, and a power conversion efficiency of 6.31% under 1 sun illumination (100 mW cm−2). Interestingly, the co-sensitizers did not compete with each other for the absorption. Both the open circuit photovoltage and the photocurrent density were unexpectedly increased with co-sensitization which means that enhancement in photocurrents can be achieved without sacrificing the open circuit photovoltage for the co-sensitized solar cells, once the electron recombination and dye aggregation are retarded by the co-sensitization.

Highly flexible TiO2/C nanofibrous film for flexible dye-sensitized solar cells as a platinum- and transparent conducting oxide-free flexible counter electrode

In this study, highly flexible TiO2/C nanofibrous film was fabricated via electrospinning followed by thermostabilization and carbonizaiton. These nanofibers (NFs) composed of carbon and TiO2 nanoparticles (NPs) with incorporation of TiO2 NPs into carbon matrix. The content of polyvinylpyrrolidone (PVP) and titanium (IV) isopropoxide (TiP) were adjusted to optimize the performance of the TiO2/C nanofibrous film. The results show that the average diameter of TiO2/C NFs and the content of carbon in NFs decreased as the proportion of PVP increased. With addition of PVP, TiO2 NPs distributed more uniformly. With increase of TiP, the average diameter and content of TiO2 increased. As a result, the conductivity decreased with the increase of PVP and TiP. While, the flexibility increased, reaching a best value before decreasing as the PVP and TiP increased. The TiO2/C nanofibrous film presented best flexibility with the content of PVP and TiP of 50% and 0.7g. Notably, the flexible TiO2/C nanofibrous film showed pleasurable catalytic activity. Therefore, the TiO2/C nanofibrous film served as platinum (Pt)- and transparent conducting oxide (TCO)-free counter electrode (CE) for flexible dye-sensitized solar cells (FDSSCs). Besides, the TiO2/C nanofibrous film CE withstood large deformation of bending and exhibited excellent bending stability.

The charge transport characterization of the polyaniline coated carbon fabric as a novel textile based counter electrode for flexible dye-sensitized solar cell

Implementation of textile based counter electrode with appreciable photovoltaic performances is a persistent objective for flexible dye-sensitized solar cells. The polyaniline (PANi) coated carbon fabric (CF) is launched as a novel flexible textile based counter electrode (CE) using different polymerization methods including chemical oxidation polymerization (COP), chemical vapor polymerization (CVP) and electropolymerization (EP) in current investigation. The electropolymerized PANi counter electrode exhibits lower charge transfer resistance (Rct) of 0.91ohm cm2 compared to CVP (1.89ohm cm2) and COP (12.18ohm cm2) techniques. As a result, electropolymerized PANi represents higher conductivity, more porosity and higher order of molecular structure which facilitates charge transfer on the counter electrode/electrolyte interface and provides sufficient electrocatalytic activity towards reduction of tri-iodide (I3−). In addition, electropolymerized PANi shows lower charge transfer than that of Pt (0.94ohm cm2) as well as an over 7% improvement in open circuit voltage at commendable overall power conversion efficiency (PCE) of 3.81%. Remarkably, the advantageous of low cost, easy and reproducible PANi synthesis, and flexible, cheap and chemical stable carbon fabric, opens up new opportunities in the development of high performance flexible textile based solar cell for energy supply in smart textiles applications.

Elektroda iz ogljikovih nanocevk za tankoplastne barvno občutljive sončne celice

Elektroda iz ogljikovih nanocevk za tankoplastne barvno občutljive sončne celice

Branched open-ended TiO2 nanotubes for improved efficiency of flexible dye-sensitized solar cells

The anatase branched open-ended titanium dioxide (TiO2) nanotubes (NTs) are prepared using a combined method of electrospinning, hydrothermal processing and calcination. The branched open-ended TiO2 NT (BOTNT) is composed a trunk of a large sized NT, from which out growth many branches consisting of single-crystalline TiO2 nanosheets (NSs) and small NTs. The morphology and microstructure of the BOTNTs can be controlled by varying with the hydrothermal treatment time. When it is used in flexible dye-sensitized solar cells (FDSSCs) as multifunctional layer covering on the carbon nanotubes (CNTs) incorporated TiO2 (CNTs/TiO2) nanorods (NRs) layer, a high conversion efficiency of 4.70% is obtained. This efficiency is much higher than that of the cell assembled by the single-layer CNTs/TiO2 NRs film. This is attributed to the great increase in light harvesting efficiency, resulting from excellent light-scattering ability and high specific surface area for dye loading of the BOTNTs. Furthermore, the excellent electron transport ability of the BOTNTs due to their high level of interconnectivity, improves the performance of FDSSCs.

The preparation of flexible Al2O3/C film and application in flexible dye-sensitized solar cells

The flexible Al2O3/carbon composite nanofibers (ACNFs) film was synthesized by electrospinning. And the effects of carbonization temperature on the structures and properties of ACNFs were investigated. All the obtained ACNFs had rough surface and random orientations, and the alumina nanostructures were closely jointed to the carbon nanofibers. Besides, the crystallinity of alumina and carbon increased with carbonization temperature. As a result, the flexural property of ACNFs film decreased, and the electrical property greatly increased with the increase of carbonization temperature. When the carbonization temperature was 900°C, the flexible ACNFs composite film was used as a counter electrode for flexible dye-sensitized solar cells. A power conversion efficiency of 2.84% was achieved. If the catalyst activity of the film was further improved, the conversion efficiency may be further improved.

The application of highly flexible ZrO2/C nanofiber films to flexible dye-sensitized solar cells

The highly flexible ZrO2/C nanofiber film was fabricated by electrospinning followed by heat treatment of stabilization and carbonization. The effects of carbonization temperature on the morphology, microstructure, and performance of ZrO2/C nanofiber film were investigated. As the temperature increases, the tetragonal phase of the ZrO2 nanoparticles gradually transformed into monoclinic phase. As a result, the mechanical and electrical properties of the ZrO2/C nanofiber film were improved. When the temperature reached 1100 °C, the ZrO2/C nanofiber film exhibited the best flexibility with the flexural modulus of 6.24 ± 0.08 MPa, the highest conductivity of 476.5 S/m, and promising electrocatalytic activity. These improvements can be ascribed to the phase transition toughening effect of ZrO2 nanoparticles, the increase in oxygen vacancy concentration in ZrO2, and the improvement in graphitization of carbon matrix. Hence, the ZrO2/C nanofiber film served as a counter electrode for flexible dye-sensitized solar cells, and an efficiency of 2.97% was achieved.

Titanium mesh supported TiO2 nanowire arrays/upconversion luminescence Er3+-Yb3+ codoped TiO2 nanoparticles novel composites for flexible dye-sensitized solar cells

Ti-mesh supported TiO2 nanowire arrays (NWAs)/upconversion luminescence Er3+-Yb3+ codoped TiO2 nanoparticles (UC-EY-TiO2 NPs) composite structured photoanodes for fully flexible dye sensitized solar cells (DSSCs) were firstly constructed via a hydrothermal and spin coating process. UV–vis-NIR absorption spectra of the TiO2 NWAs/UC-EY-TiO2 NPs composites exhibited strong absorption around near infrared (NIR) 980nm. The composites excited by 980nm NIR laser could emit upconversion fluorescence at 489, 526, 549 and 658nm, which expanded the spectral response range and sunlight capturing capability of formed flexible DSSCs. Moreover, the TiO2 NWAs/UC-EY-TiO2 NPs was coated with an Nb2O5 thin layer to further suppress electron recombination losses. The complete flexible DSSCs based on Nb2O5 coated TiO2 NWAs/2.0mol% Er3+-1.0mol% Yb3+ codoped TiO2 NPs photoanode and Pt/ITO-PEN counter electrode exhibited an enhanced photon to current conversion efficiency of 8.10%, a 68% improvement compared to TiO2 NWAs/undoped TiO2 NPs based DSSCs (4.82%).

A paper-based electrode using a graphene dot/PEDOT:PSS composite for flexible solar cells

We have synthesized a metal-free composite ink that contains graphene dots (GDs) and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) that can be used on paper to serve as the counter electrode in a flexible dye-sensitized solar cell (DSSC). This paper-based GD/PEDOT:PSS electrode is low-cost, light-weight, flexible, environmentally friendly, and easy to cut and process for device fabrication. We determined the GD/PEDOT:PSS composite effectively fills the dense micro-pores in the paper substrate, which leads to improved carrier transport in the electrode and a 3-fold enhanced cell efficiency as compared to the paper electrode made with sputtered Pt. Moreover, the DSSC with the paper electrode featuring the GD/PEDOT:PSS composite did not fail in photovoltaic tests even after bending the electrode 150 times, whereas the device made with the Pt-based paper electrode decreased in efficiency by 45% after such manipulation. These exceptional properties make the metal-free GD/PEDOT:PSS composite ink a promising electrode material for a wide variety of flexible electronic applications.

A dual function of high efficiency quasi-solid-state flexible dye-sensitized solar cell based on conductive polymer integrated into poly (acrylic acid-co-carbon nanotubes) gel electrolyte

A series dual function of quasi-solid-state gel electrolytes with high conductivity and good catalytic ability were prepared by integrating the carbon nanotubes (CNTs) and conducting polymers including polypyrrole (PPy), polyaniline (PANI) and poly(3,4-ethylenedioxythiophene) (PEDOT) into poly (acrylic acid) (PAA) gel, showing significant improvement in electrochemical and photoelectrochemistry capability used in dye-sensitized solar cells (DSSCs). These novel electrolytes provide three dimensional network structures for transporting electrons, giving a similar conduction mechanism to that of I−/I3− liquid electrolyte system. The electrochemical performance of the CoS/Ag/Ti counter electrode (CE) was evaluated by electrochemical impedance spectroscopy, which revealed that the CoS/Ag/Ti CE exhibited excellent electrocatalytic ability for these novel electrolytes as well as that of in I−/I3− liquid system. The quasi-solid-state flexible DSSC fabricated with the CoS/Ag/Ti CE and novel gel electrolytes integrated PPy, PANI and PEDOT achieved enhanced power conversion efficiency of 6.89%, 7.01% and 7.20% under the irradiation of 100mWcm−2, which have much approached that of the DSSC (7.35%) based on Pt electrode and I−/I3− liquid electrolyte.

Nickel tetraphenylporphyrin doping into ZnO nanoparticles for flexible dye-sensitized solar cell application

In this study, we report on ZnO-based flexible dye-sensitized solar cells (DSCs) doped with different concentrations of 5,10,15,20-tetraphenyl-21H,23H-porphyrin nickel(II) (NiTPP). The photoelectrodes were prepared by blade coating, followed by a hot-compression technique. The effects of NiTPP doping on the surface morphology, structural, optical, and photovoltaic properties were studied. The surface morphology was observed by scanning electron microscopy (SEM), which confirmed the presence of NiTPP particles and also some aggregated particles visible at higher doping concentrations. The structural properties were examined by X-ray diffraction analysis and Raman spectroscopy, which confirmed the hexagonal wurtzite ZnO structure. The crystallite size of the ZnO nanoparticles (NPs) increased while the lattice strain decreased with increasing NiTPP doping concentration. The increment in the crystallite size might have induced light scattering inside the film to some extent. Optical absorption spectra showed the broadening of the spectrum in the lower-wavelength region, and a new absorption peak appeared (at 422 nm) as an effect of NiTPP doping. The red and blue shifts were observed for that peak as an effect of various doping concentrations. The Raman study of the films showed that there is no significant changes in the ZnO or NiTPP crystallite structure because of the NiTPP doping at different concentrations. Photocurrent–voltage (I–V) analysis showed that the 0.7%-NiTPP-doped cell attained the highest light-to-electric conversion efficiency of 2.7% in this investigation, which was about 42% higher than that of a non-NiTPP-doped cell.

Efficient light harvesting from flexible perovskite solar cells under indoor white light-emitting diode illumination

This is the first report of an investigation on flexible perovskite solar cells for artificial light harvesting by using a white light-emitting diode (LED) lamp as a light source at 200 and 400 lx, values typically found in indoor environments. Flexible cells were developed using either low-temperature sol–gel or atomic-layer-deposited compact layers over conducting polyethylene terephthalate (PET) substrates, together with ultraviolet (UV)-irradiated nanoparticle TiO2 scaffolds, a CH3NH3PbI3–xClx perovskite semiconductor, and a spiro-MeOTAD hole transport layer. By guaranteeing high-quality carrier blocking (via the 10–40 nm-thick compact layer) and injection (via the nanocrystalline scaffold and perovskite layers) behavior, maximum power conversion efficiencies (PCE) and power densities of 10.8% and 7.2 μW·cm–2, respectively, at 200 lx, and 12.1% and 16.0 μW·cm–2, respectively, at 400 lx were achieved. These values are the state-of-the-art, comparable to and even exceeding those of flexible dye-sensitized solar cells under LED lighting, and significantly greater than those for flexible amorphous silicon, which are currently the main flexible photovoltaic technologies commercially considered for indoor applications. Furthermore, there are significant margins of improvement for reaching the best levels of efficiency for rigid glass-based counterparts, which we found was a high of PCE ~24% at 400 lx. With respect to rigid devices, flexibility brings the advantages of being low cost, lightweight, very thin, and conformal, which is especially important for seamless integration in indoor environments.

Solution-Processed Transparent Nickel-Mesh Counter Electrode with in-Situ Electrodeposited Platinum Nanoparticles for Full-Plastic Bifacial Dye-Sensitized Solar Cells.

A new type of embedded metal-mesh transparent electrode (EMTE) with in-situ electrodeposited catalytic platinum nanoparticles (PtNPs) is developed as a high-performance counter electrode (CE) for lightweight flexible bifacial dye-sensitized solar cells (DSSCs). The thick but narrow nickel micromesh fully embedded in a plastic film provides superior electrical conductivity, optical transmittance, and mechanical stability to the novel electrode. PtNPs decorated selectively on the nickel micromesh surface provide catalytic function with minimum material cost and without interfering with optical transparency. Facile and fully solution-processed fabrication of the novel CE is demonstrated with potential for scalable and cost-effective production. Using this PtNP-decorated nickel EMTE as the CE and titanium foil as the photoanode, unifacial flexible DSSCs are fabricated with a power conversion efficiency (PCE) of 6.91%. By replacing the titanium foil with a transparent ITO-PEN photoanode, full-plastic bifacial DSSCs are fabricated and tested, demonstrating a remarkable PCE of 4.87% under rear-side illumination, which approaches 85% of the 5.67% PCE under front-side illumination, among the highest ratio in published results. These promising results reveal the enormous potential of this hybrid transparent CE in scalable production and commercialization of low-cost and efficient flexible DSSCs.