Fiber-shaped Dye-sensitized Solar Cells Research Articles

Novel Strategy towards Efficiency Enhancement of Flexible Optoelectronic Devices with Engineered M13 Bacteriophage

Plasmonic nanostructures, which exhibit notable localized surface plasmon resonance (LSPR) properties, are a promising approach for improving the efficiency of fiber‐shaped dye‐sensitized solar cells (FDSSCs) and flexible organic light‐emitting diodes (FOLEDs). Herein, novel plasmonic nanostructure is successfully synthesized via the self‐densification of gold nanoparticles (Au NPs) onto a genetically engineered M13 bacteriophage template. The synthesized Au NP‐M13 bio‐nanostructure show extraordinary gap‐plasmon effects and significantly enhanced LSPR properties compared to randomly dispersed Au NPs for both solid‐state FDSSCs (SS‐FDSSCs) and FOLEDs. Briefly, a power conversion efficiency (PCE) increment of 40.7% is recorded for the Au metallic NPs‐anchored M13 bacteriophage (Au NPs‐M13) enhanced SS‐FDSSCs; whereas an external quantum efficiency (EQE) increment of 47.2% is achieved for the Au NPs‐M13 enhanced FOLEDs.

Improved device performance with 4-amino-TEMPO derivatives for fiber dye-sensitized solar cells and organic light-emitting diodes

4-Amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-Amino-TEMPO; 4AT), has been used as a photo-catalyst to boost photo-catalytic activity, are a promising approach for improving the efficiency of fiber-shaped dye-sensitized solar cells (FDSSCs) and fiber-shaped organic light-emitting diodes (FOLEDs). Herein, one of the 4AT, 4-p-toluenesulfonamide-TEMPO (ATpTS) was successfully synthesized by using a dropwise method. The synthesized ATpTS showed an extraordinary photo-catalytic effect and significantly enhanced performance compared to the pristine-based active layer for both solid-state electrolytes of the FDSSCs (SS-FDSSCs) and FOLEDs. Briefly, a power conversion efficiency increment of 22.8% is recorded for the ATpTS-enhanced SS-FDSSCs; whereas an external quantum efficiency increment of 45.4% is achieved for the ATpTS-enhanced FOLEDs.

Tailoring the Structure–Property Relationships of Innovative Flowerlike TiO2 Structures in a Fiber-Shaped Dye-Sensitized Solar Cell

Tailoring the Structure–Property Relationships of Innovative Flowerlike TiO₂ Structures in a Fiber-Shaped Dye-Sensitized Solar Cell

Solid state fiber-dye sensitized solar cells (SS-FDSSC): A mini review

Fiber-shaped dye-sensitized solar cells (FDSSC) can fulfill the energy demand of portable electronic devices, specifically in remote applications; however, the stability of such systems is a bottleneck, due to the use of liquid electrolytes. Liquid electrolytes pose evaporation problem, leakage issue, and possibility of short circuit, hence solid electrolytes are the ultimate solution for long-lasting FDSSCs. Considering this, recent advances in solid electrolytes, photoanode materials, and counter electrode materials are summarized for all solid-FDSSCs. A special focus has been given to the types of solid electrolytes, their synthesis, and associated photovoltaic performance. The performance parameters of solid electrolytes, such as ionic conductivity, light transmittance, and photovoltaic performance are summarized in this review. Furthermore, the works related to novel photoanode and counter electrode materials employing solid electrolytes are also included in the review. A comparison table of power conversion efficiencies and lifetime of solid-state-FDSSCs is provided, which shows that the highest efficiency is possible for Li-TFSI (bis(trifluoromethane)sulfonimide lithium salt) soaked Iodide electrolytes. Better transparency and conductivity of such electrolytes are key parameters in imparting high efficiency of such electrolytes, i.e. 6.5%.

Efficient and Stable Fiber Dye-Sensitized Solar Cells Based on Solid-State Li-TFSI Electrolytes with 4-Oxo-TEMPO Derivatives.

Fiber-shaped dye-sensitized solar cells (FDSSCs) with flexibility, weavablity, and wearability have attracted intense scientific interest and development in recent years due to their low cost, simple fabrication, and environmentally friendly operation. Since the Grätzel group used the organic radical 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) as the redox system in dye-sensitized solar cells (DSSCs) in 2008, TEMPO has been utilized as an electrolyte to further improve power conversion efficiency (PCE) of solar cells. Hence, the TEMPO with high catalyst oxidant characteristics was developed as a hybrid solid-state electrolyte having high conductivity and stability structure by being integrated with a lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) film for FDSSCs. The optimized 4-Oxo TEMPO (OX) based solid-state FDSSC (SS-FDSSC) showed the PCE of up to 6%, which was improved by 34.2% compared to that of the reference device with 4.47%. The OX-enhanced SS-FDSSCs reduced a series resistance (Rs) resulting in effective electron extraction with improved short-circuit current density (JSC), while increasing a shunt resistance (Rsh) to prevent the recombination of photo-excited electrons. The result is an improvement in a fill factor (FF) and consequently a higher value for the PCE.

Self-powered and flexible integrated solid-state fiber-shaped energy conversion and storage based on CNT Yarn with efficiency of 5.5%

Self-powered and flexible integrated solid-state fiber-shaped photo capacitors (SS-FPCs), which combine energy-harvesting and energy-storage functions in a single device, have drawn a lot of attention as potential applications in wearable electronics. Herein, a flexible carbon nanotube yarn (CNTY) with improved mechanical and electrical properties is used as a shared electrode to create SS-FPCs. In addition, CNTY was doped into n- and p-type using polyethyleneimine (PEI) and iron (III) chloride (FeCl3) to improve the electrocatalytic behavior of CNTY, respectively. The optimized SS-FPC based on p-type material-doped CNTY, which integrates the high specific capacitance of the solid-state fiber-shaped electrochemical energy storage (SS-FES) unit with 78.26 mF cm−2 and a high power conversion efficiency (PCE) of the solid-state fiber-shaped dye-sensitized solar cells (SS-FDSSCs) unit with 5.50%, exhibits a remarkable overall energy conversion efficiency of up to 4.69% and excellent discharging time of about 6 min owing to the synergistic action of the two units. Compared to traditional integrated power systems, our self-powered and flexible integrated SS-FPCs are lightweight, flexible, affordable, and suitable for special applications, especially fabric for wearable electronics.

Improved Light Harvesting of Fiber-Shaped Dye-Sensitized Solar Cells by Using a Bacteriophage Doping Method.

Fiber-shaped solar cells (FSCs) with flexibility, wearability, and wearability have emerged as a topic of intensive interest and development in recent years. Although the development of this material is still in its early stages, bacteriophage-metallic nanostructures, which exhibit prominent localized surface plasmon resonance (LSPR) properties, are one such material that has been utilized to further improve the power conversion efficiency (PCE) of solar cells. This study confirmed that fiber-shaped dye-sensitized solar cells (FDSSCs) enhanced by silver nanoparticles-embedded M13 bacteriophage (Ag@M13) can be developed as solar cell devices with better PCE than the solar cells without them. The PCE of FDSSCs was improved by adding the Ag@M13 into an iodine species (I−/I3−) based electrolyte, which is used for redox couple reactions. The optimized Ag@M13 enhanced FDSSC showed a PCE of up to 5.80%, which was improved by 16.7% compared to that of the reference device with 4.97%.

Decoration of TiO2 nanoparticles on TiO2 microcone array with holes as photoanodes of fiber-shaped dye-sensitized solar cells

Fiber-shaped dye-sensitized solar cell (FDSC) is one of efficient energy generation devices for soft electronics, owing to low-cost and dim-light operable features. The key component of FDSC is photoanode, which is responsible for absorbing incident light and generating charges. Designing TiO2 structure is significant for fabricating efficient photoanode of FDSC. In this study, it is the first time to fabricate TiO2 nanoparticle-decorated TiO2 microcone array (TMC) with holes using simple two-step anodization and dip-coating processes as semiconductor on photoanode of FDSC. Different H2SO4 concentrations is used to creating holes on TMC. Holes are generated on TMC in anodization process, but TMC are detached from Ti wire more seriously when higher H2SO4 concentration is used. The optimized photoanode of FDSC is prepared using 30 mM H2SO4. The optimized FDSC shows solar-to-electricity conversion efficiency (η) of 2.52%, while the FDSC with the pure TMC photoanode only shows η of 1.68%. The better photovoltaic performance of FDSC comprising TiO2 nanoparticle-decorated TMC with holes photoanode is owing to abundant contacts between TMC and TiO2 nanoparticles and high surface area of TiO2 nanoparticles for dye adsorption. The highest collection efficiency of 92.21% is also achieved for the FDSC with the optimized photoanode, analyzed using intensity modulated photocurrent/voltage spectroscopy spectra.

Highly efficient long thin-film fiber-shaped dye sensitized solar cells based on a fully organic sensitizer

In light of the ever-growing demand of modern electronics for wearable integrated optoelectronic devices, Fiber-shaped Dye-Sensitized Solar Cells (FDSSCs) have gained increasing interest over the last years as suitable energy production systems for the development of the next generation of smart products. To fulfill the wearable concept, it is important to design long and flexible thin-film FDSSCs capable of adapting to curved surfaces such as the human body. In this study, for the first time, several key parameters towards the optimization of long and flexible FDSSCs based on inexpensive TiO2 as photoanode material and a fully organic thiazolo [5,4-d]thiazole-based sensitizer (TTZ5) were studied. First, the influence of photoanode thickness on photovoltaic performance was evaluated in 3.5 cm-long devices, for which an optimal thickness of 10 μm was identified, obtaining a maximum PCE of 1.57 ± 0.15%. Long (10 cm) complete FDSSCs were then fabricated, using thin layer photoanodes of about 5 μm which were instead found to be the optimal choice for such devices. The as-obtained FDSSCs based on TTZ5 possess dimensions appealing for future applications while also delivering a remarkable PCE of 1.23 ± 0.04%, thus paving the way for further optimization of thin-film flexible long FDSSCs based on organic sensitizers.

Design of highly ordered hierarchical catalytic nanostructures as high-flexibility counter electrodes for fiber-shaped dye-sensitized solar cells

Ordered array structures will greatly reduce the stress formation in wearable electric devices during dynamic bending operation. In this work, highly flexible TiN-based fiber counter electrodes (FCEs) were designed via a post-ammonization treatment on the hydrothermally grown TiO2 nanowire arrays. Results show that the obtained TiN nanorod arrays (NRAs) are well aligned with a diameter of 200–320 nm and a length of several hundred nanometers to ∼1 μm. Moreover, fiber-shaped dye-sensitized solar cells assembled using TiN FCEs showed the maximum photoelectric conversion efficiency (PCE) of 5.69%, which is 16.3% higher than that of the ones based on Pt FCEs. Analysis indicated that this enhancement in PCE could be mainly due to the better electrochemical catalytic activity of TiN NRAs. Furthermore, the optimizations of the nanoscale morphologies of TiN NRAs suggest that both small diameters and large lengths can benefit the PCE and the dynamic bending stability, while the diameters show a major influence on them. The optimal FCEs show an ultralow decay rate of 0.017‰ per bending cycle.

Fractional structured molybdenum oxide catalyst as counter electrodes of all-solid-state fiber dye-sensitized solar cells

A novel hierarchical solution-processed fractional structured molybdenum oxide (MoO3) catalyst is fabricated from tricarbonyltris (propionitrile) molybdenum and used as the counter electrode of all-solid-state fiber-shaped dye-sensitized solar cells (S-FDSSC). The Tafel plot results and electrical impedance spectroscopy suggest that the use of the fractional structured MoO3 catalyst enhances the efficiency of the reduction of I3− to 3I− at the counter electrode/electrolyte interface. Because of the improvements of the short-current circuit and fill factor, the power conversion efficiency of the MoO3-modified S-FDSSC improves by 60% compared with that of the reference S-FDSSC. In addition, because of the robust fractional structure of MoO3, the MoO3-modified S-FDSSC maintains 90% and 95% of efficiency after 350-fold bending and the incident light angle dependency test, respectively. At 65% humidity and at 65 °C, the power conversion efficiency of the MoO3-modified device decreases by <20% after 350 h of storage, while that of the reference device drops by more than 70%.

Tuning electrolyte configuration and composition for fiber-shaped dye-sensitized solar cell with poly(vinylidene fluoride-co-hexafluoropropylene) gel electrolyte

Efficient energy generation device is desired to couple with soft electronics for driving devices. Due to frequent uses of soft electronics in indoor conditions, flexible fiber-shaped dye-sensitized solar cell (FDSC) is regarded as the most promising energy generation device due to high light-to-electricity conversion maintenance under weak dim light. Using gel electrolyte to assemble FDSC cannot only restrict electrolyte leakage but also improve device flexibility and stability especially under bending conditions. In this study, poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) gel electrolyte is used to fabricate FDSC composed of curled TiO2 nanotube/Ti wire photoanode and Pt counter electrode. It is the first time to control gel electrolyte configuration by adding different PVdF-HFP concentrations, and to optimize iodine concentration in electrolyte regarding to redox ability and electrolyte transmittance. Configuration of gel electrolyte is carefully analyzed to define porous layer and concrete layer of polymer for accumulating liquid electrolyte and inhibiting leakage and evaporation. The highest solar-to-electricity conversion efficiency of 6.32% is obtained for FDSC with 9% PVdF-HFP and 0.04 M I2 in electrolyte, due to well-defined cross-linking structure, abundant redox reactions, and high incident-light illumination through electrolyte. Electrochemical impedance spectroscopy and intensity-modulated photocurrent/photovoltage spectroscopy are used to analyze charge-transfer resistance and charge-collection efficiency.

Improving the efficiency of thin-film fiber-shaped dye-sensitized solar cells by using organic sensitizers

Fiber-shaped Dye-Sensitized Solar Cells (DSSFs) represent one of the most interesting technologies aimed at the light harvesting and the production of electricity for wearable applications. In order to boost DSSFs commercialization, their production costs and environmental impact must be reduced. To this end, a suitable strategy could be to build thin film-based devices endowed with metal-free organic sensitizers, exploiting their higher molar extinction coefficients compared to typical ruthenium-containing organometallic dyes. In this work, three thiazolo[5,4-d]thiazole-based organic dyes, TTZ3, TTZ5 and TTZ7, capable of strongly absorb visible light, were used for the first time to manufacture titanium wire-based DSSFs. DSSFs based on a thin TiO2 layer (5 μm) sensitized with the three organic dyes were prepared and tested and the obtained results show that power conversion efficiencies for the organic dyes (0.80%) are higher than that obtained with the reference N719 dye (0.45%). An efficiency of 0.99% with short circuit current density equal to 3 mA/cm2 was achieved when the TTZ7-based DSSFs were tested in diffuse illumination condition, highlighting the supremacy of these dyes compared to the metal-organic reference. The excellent photovoltaic performances of TTZ dyes were attributed to their better light harvesting properties, resulting in the production of higher photocurrent densities, which was confirmed by the electrochemical impedance spectroscopy (EIS) analysis. The superiority of organic dyes on DSSFs performances compared to N719, shown for the first time in this work, support the real possibility to apply these molecules for the preparation of efficient light-harvesting devices based on thin film photoanodes.

Flexible self-powered fiber-shaped photocapacitors with ultralong cyclelife and total energy efficiency of 5.1%

Fiber-shaped photocapacitors (FPCs) combine functions of energy harvesting and storage in a single device has attracted great attention for their potential applications in portable and wearable electronics. However, the FPCs suffer from the low photochemical-electric energy conversion efficiency and poor cycling stability due to the limitation of the fiber-shaped electrodes. Herein, high crystalline conductive polymer fibers with high electrocatalytic activity and energy storage efficiency for both energy harvest and energy storage are prepared and used as shared electrode to fabricate efficient and stable FPCs. Synergistically, the FPCs fabricated by combining a fiber-shaped dye-sensitized solar cell and a fiber-shaped supercapacitor into one device by sharing one electrode exhibit a remarkable total photochemical-electric energy conversion efficiency up to 5.1%, which is higher than that of reported energy fibers and even close to those of the planar devices in previous reports. Meanwhile, the fabricated FPCs show superior cycling capability for more than 1700 photocharge/galvanostatic discharge cycles (63 days) with efficiency retention of 70.6%. The FPCs woven into the textile can steadily power the ultraviolet photodetector after photocharged in natural sunlight, showing potential in the application of wearable electronics.

Bamboo-Like Nitrogen-Doped Carbon Nanotube Forests as Durable Metal-Free Catalysts for Self-Powered Flexible Li-CO2 Batteries.

The Li-CO2 battery is a promising energy storage device for wearable electronics due to its long discharge plateau, high energy density, and environmental friendliness. However, its utilization is largely hindered by poor cyclability and mechanical rigidity due to the lack of a flexible and durable catalyst electrode. Herein, flexible fiber-shaped Li-CO2 batteries with ultralong cycle-life, high rate capability, and large specific capacity are fabricated, employing bamboo-like N-doped carbon nanotube fiber (B-NCNT) as flexible, durable metal-free catalysts for both CO2 reduction and evolution reactions. Benefiting from high N-doping with abundant pyridinic groups, rich defects, and active sites of the periodic bamboo-like nodes, the fabricated Li-CO2 battery shows outstanding electrochemical performance with high full-discharge capacity of 23 328 mAh g-1 , high rate capability with a low potential gap up to 1.96 V at a current density of 1000 mA g-1 , stability over 360 cycles, and good flexibility. Meanwhile, the bifunctional B-NCNT is used as the counter electrode for a fiber-shaped dye-sensitized solar cell to fabricate a self-powered fiber-shaped Li-CO2 battery with overall photochemical-electric energy conversion efficiency of up to 4.6%. Along with a stable voltage output, this design demonstrates great adaptability and application potentiality in wearable electronics with a breath monitor as an example.

A highly elastic self-charging power system for simultaneously harvesting solar and mechanical energy

Developing lightweight, flexible and sustainable power sources is desirable and favorable for wearable electronics with the rapid advancement of portable devices. Here, a highly elastic and sustainable power source is fabricated for harvesting and storing energy simultaneously from ambient sunshine and human movement. Flexible fiber-shaped dye-sensitized solar cells are smartly integrated with triboelectric nanogenerators and serve as generating set. The supercapacitors as energy storage devices can store direct current energy for the solar cells and alternating current energy from the triboelectric nanogenerators after rectified at the same time. Furthermore, the supercapacitors are easily integrated with generating set due to the same electrode materials with triboelectric nanogenerators. Due to the all flexible devices, the size of the whole power system can be easily tuned and connected with electronic devices to create self-powered wearable electronics.

Flexible, controllable and angle-independent photoelectrochromic display enabled by smart sunlight management

In this work, we present a newly designed photoelectrochromic smart windows (PECSW) comprising of a large-scale electrochromic device (ECD) and several integrated fiber-shaped dye-sensitized solar cells (FDSSCs). In this configuration, to avoid shading sunlight for each other, the FDSSCs twine around the ECD and serve as frames. Different from rigid planar solar cells, the FDSSCs are suitable to be integrated (series or parallel connection) to output desired power to drive the ECDs. More importantly, the angle dependence of the FDSSC's output on incident light is extremely low due to the unique cylindrical configuration, which brings convenience for the installation of the PECSW on the building external wall. Thanks to the high flexibility of the FDSSCs, the solar cells can be integrated with flexible ECDs for special applications. It was demonstrated that the PECSW can be directly driven by sunlight and the transmittance of the smart window can be adjusted by the light intensity. In addition, the PECSW also can be utilized as photoelectrochromic supercapacitor for energy storage and its reversible color variation can simultaneously monitor the level of stored energy. The FDSSCs based PECSW represents a new opportunity for emerging smart window technologies.

Effect of TiO2-rGO heterojunction on electron collection efficiency and mechanical properties of fiber-shaped dye-sensitized solar cells

It is demonstrated that the incorporation of graphene materials into oxide-based photoanodes can greatly increase the photoelectrochemical devices’ performances. In this work, reduced graphene oxide (rGO) has been incorporated into P25-TiO2 nanoparticle (NP) based photoanodes for fiber-shaped dye-sensitized solar cells (FDSSCs). Results showed that the rGO nanosheets have been uniformly dispersed within P25 nanoparticle layers, and, as expected, the incorporation of rGO increased the FDSSCs’ short current density from 8.344 to 12.935 mA cm−2, open circuit voltage from 0.775 to 0.798 V, resulting into their power conversion efficiency (PCE) from 3.940% to 5.364%. This large increasement in PCE could be due to two aspects, i.e. the improved electron transport properties via rGO and the enhanced separation of photogenerated hole–electron pairs via rGO-TiO2 heterojunction. Furthermore, the incorporation of rGO can also make the FDSSCs have good mechanical properties, which is very crucial for their future applications in smart wearable electronics. In addition, based on our analysis, a possible rGO/multi-NP coupling enhancement mechanism was proposed.

One-step facile hydrothermal synthetic route to prepare CoS nanoplates as counter electrode material for fiber-shaped dye-sensitized solar cells

CoS nanoplates and nanoparticles films were successfully grown on carbon fibers (CF) via one-step process and used in fiber-shaped dye sensitized solar cells as counter electrodes. The electrocatalytic ability of CF accompanied with CoS nanoplates electrode was comparable with the expensive Pt wire, and obviously superior to the CF covered by CoS nanoparticles film. The results were believed to originate from: (1) the enough void space among CoS nanoplates allows easier redox ion diffusion; (2) the two-dimensional nanoplates favor the longer distance electron transport with less diffusive hindrance than the randomly depositing nanoparticles film, where the electrons have to cross many tiny particle boundaries that can trap electrons.

One step hydrothermal synthesis of vertical Ni-Mo-S nanosheet array as the counter electrode for FDSC

In order to further improve electrocatalytic ability of MoS2 counter electrode(CE) in fiber-shaped dye sensitized solar cells(FDSSCs), Ni element was introduced and Ni-Mo-S nanosheet array was prepared by a simple one-step hydrothermal process. By utilizing synergetic effects between two transition metals and more catalytically active edges in Ni-Mo-S nanosheet array, lower series transfer resistance(Rct) at the interface of CE/electrolyte in the electrochemical impedance spectra (EIS) measurement and higher cathodic peak current in the cyclic voltammetry (CV) measurement were obtained when compared with MoS2, indicating Ni-Mo-S processed superior electrocatalytic activity to MoS2. As a result, power conversion efficiency of Ni-Mo-S based FDSSC(6.3%) was found to be higher than MoS2-based FDSSC (4.2%), comparable to Pt based FDSSC(6.4%).