Absorption Of Dye-sensitized Solar Cells Research Articles

Enhanced Efficiency of Dye-Sensitized Solar Cells by Controlled Co-Adsorption Self-Assembly of Dyes.

Single dyes typically exhibit limited light absorption in dye-sensitized solar cells (DSSCs). Thus, cosensitization using two or more dyes to enhance light-harvesting efficiency has been explored; however, the aggregation of dyes can adversely affect electron injection capabilities. This study focused on the design and synthesis of three dyes with a common carbazole donor for DSSCs: DZ102, TZ101, and JM102. JM102 broadens the absorption spectrum by replacing the benzoic acid electron acceptor of TZ101 with acetylenic benzoic acid. A cosensitized DSSC device based on CO-1 [DZ102:TZ101 = 1:1 (50 μM:50 μM)] achieved a short-circuit current density of 19.4 mA/cm2 and a power conversion efficiency of 10.9%. For the first time, the molecular interactions between the dyes in the photoanode were demonstrated using cyclic voltammetry, which revealed the presence of intermolecular forces. Adsorption kinetics further indicated that these forces promoted the self-assembly of dyes during adsorption, which resulted in a cosensitization adsorption amount greater than the sum of the individual dye adsorptions. This study provides novel insights into the selection of cosensitizing dyes for DSSCs.

Study of Band Gap Reduction and Enhanced light Absorption in DSSC’s using N-TiO2 and Azo Dye Composites

This research delves into enhancing Dye-Sensitized Solar Cells (DSSCs) using Nitrogen added Titanium Dioxide (N-TiO2) nanoparticles. Nitrogen is employed to reduce TiO2's band gap, thereby enhancing its light absorption capabilities. Azo dyes namely VC, RP and RM are chosen as sensitizers due to their efficient light absorption properties. UV-spectrophotometer analysis reveals superior absorption and a lower band gap in N-added TiO2 compared to pure TiO2. Additionally composites of pure TiO2, N-added TiO2 with azo dyes taken in various proportion are explored. Energy band gap of each is calculated using UV- spectrophotometer analysis. Composites made using 8% N and TiO2 with azo dyes VC and RP taken in equal ratio showed the maximum absorption for a range of frequencies from 300nm to 900nm and thus leading to the minimum energy band gap.

Enriched visible light absorption by Au-embedded Sm3+ doped TiO2 compact photoanode for enhanced dye-sensitized solar cell performance

The cooperative effect of Samarium (Sm3+)-doped TiO2 and gold nanoparticles (Au NPs) is investigated in this work to explore its potential to boost visible light absorption in dye-sensitized solar cells (DSSC). As Sm3+ exhibits PL emissions at 583 nm, 612.2 nm, 663.6 nm, and 726.3 nm, there is an overlap with the absorption region of the N719 dye and these PL emission wavelengths resulting in a rise in photocurrent density and PCE owing better UV light harvesting. Sm3+ absorption and emissions were boosted by LSPR (Localized surface plasmon resonance) of Au NPs. As a result, the Au NPs embedded Sm-doped TiO2 photoanode-based DSSC capture more visible light. Sm (0.3)-TiO2 based DSSC reports the highest PCE (η:7.2%) among a series of Sm (0.2%, 0.3%, 0.4%, and 0.5% mol) TiO2 concentrations. Further, with the addition of Au NPs into the Sm3+ -doped TiO2, the PCE is enlarged into (η: 8.33%), which is more than 60% higher than TiO2 photoanode-based DSSC (η: 5.58%).

A Study on the Effect of Gold Nanoparticles for Dye Sensitized Solar Cell Using Hibiscus Rosa-Sinensis as Photosensitizer

Dye-sensitized solar cells (DSSC) mainly use organic components as an alternative way of light harvesting element to replace the traditional silicon solar cells. N atural dye alternatively is being used as sensitizers to overcome the limitation of inorganic ruthenium dye which contains heavy metal. In this study, DSSC is expected to enhance its optical properties and light absorption by implementing gold (Au) nanoparticles. Various natural and organic sources can be extracted and acted as a photosensitizer to trap solar energy. Fresh Hibiscus Rosa-Sinensis flowers are one of the good candidates to give higher light absorption in DSSC. The characteristics of the dye photosensitizer will be observed under UV-Vis-NIR Spectrophotometer. The efficiency of complete DSSC will be determined by using LIV tester. An attempt to enhance light-harvesting efficiency and hence the light to current conversion efficiency by mixing Au nanoparticles TiO₂ paste. Au nanoparticle was selected because it can act as a medium between the dye and TiO₂ to increase the electron transmission speed. The Hibiscus dye in DSSC achieved an efficiency of 0.14%. However, the efficiency reduced to 0.000178% as Au NPs was added. The effects of the addition of Au nanoparticles are discussed.

Extraction, characterization and energy investigation of Garcinia kola, Cola Nitida and Cola Accuminata for efficient light absorption in dye-sensitized solar cells

Natural extracts were obtained from the Garcinia kola, Cola Nitida and Cola Accuminata. The extracts from Garcinia kola, Cola Nitida and Cola Accuminata were evaluated for their phytochemical, electrochemical and photovoltaic current–voltage (I-V) light-to-electricity conversion efficiency in dye-sensitized solar cells (DSSCs). This is the first time when flavonoid, garcinoic, caffeine and their derivatives from the Garcinia species will be tested for electrochemistry and for DSSCs power conversion efficiency. The results revealed that the different affinity among the three Garcinia sp.; Cola Nitida, Cola Accuminata and Garcinia kola with TiO2 semiconductor was responsible for their various adsorption, binding and light absorption transfer into the semiconductor band edge. Cyclic voltammetry of the three compounds shows a well-defined redox nature, good reversibility of electron transfer and dye regeneration. Cola Nitida NIT compound had the lowest Homo energy level (-5.130 eV) and highest Lumo energy value (-2.029 eV) than Garcinia kola and Cola Accuminata.GK compound revealed lower-charge transfer resistance than ACC and NIT. Gk sensitizer showed an improve light-to-electricity conversion efficiency (η2) = 0.14 %, FF = 0.753, Voc = 0.850 V and Jsc = 0.200 mAcm−2 under 1 sun illumination giving a standard deviation efficiency of 0.024 as compared to ACC and NIT.

Optimization of metal nanoparticles concentration in dye solution to enhance performance of dye sensitized solar cells

In this study, we incorporate metal nanoparticles of AuNP and AgNP into dye N-719 solution in order to enhance the light absorption of dye-sensitized solar cells (DSSCs) device. AuNP or AgNP was mixed into N-719 dye solution by optimized the concentration of metal NPs. The optical property of the mixtures was investigated by use of UV-Vis spectroscopy while the morphology of the solutions was captured by TEM microscopy. The performance of DSSCs was done by J-V measurement equipped with solar simulator under light illumination of 100mW/cm2. Our fabricated DSSC devices show the enhancement of current density and power conversion efficiency (PCE) with the incorporation of metal NPs into dye layer. Addition of gold nanoparticle capped by dodecanethiols (AuDT) 5.66 wt.% reveals the enhancement of PCE devices from 1.58% without AuDT as reference to 2.77% with AuDT. Similar case for the addition of AgSC8 into dye of DSSC gives the same tendencies.

The effect of plasmonic multilayered photoanode structures on the absorption of dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) have recently gained much attention, due to the low-cost materials and their cheaper manufacturing techniques. However, these cells show a weak response to incident solar photons, resulting in poor power-conversion efficiency. In this paper, we described an improvement to the optical absorption efficiency of DSSCs in the wavelength range between 350 nm and 750 nm using the surface plasmon-resonance effect of plasmonic nanoparticles. Three different structures are studied, including unilayer, bilayer, and trilayer photoanodes based on various core–shell plasmonic spherical nanoparticles made of Ag@TiO2. In all structures, the nanoparticle size is optimized to obtain broadband optical absorption. The absorption efficiency of the dye-sensitized solar cell is significantly improved, from 65.2% to 72.3%, by tuning the photoanode structure from unilayer to trilayer. The results show that a unilayer photoanode with smaller-sized nanoparticles leads to higher absorption, compared to larger sizes. The UV–vis results indicate that mixing large- and small-sized nanoparticles in bi- and trilayer photoanodes is a good approach for improving the light-harvesting efficiency of DSSCs, compared to uniformly distributed nanoparticles. A maximum short-circuit current density of 17.32 mA cm−2 is recorded for a photoanode based on a trilayer structure of Ag@TiO2 nanoparticles.

A review on spectral converting nanomaterials as a photoanode layer in dye‐sensitized solar cells with implementation in energy storage devices

AbstractThe present review article aims at the application of rare‐earth‐based titanium dioxide nanocrystals as spectral converters in photovoltaic devices, with special focus on dye‐sensitized solar cells (DSSCs). Additionally, the implementation of DSSCs in energy storage, more importantly, DSSCs and lithium‐ion batteries (LIB) integrated devices are systematically described. The absorption in DSSCs is mainly confined to the visible solar spectrum, which is one of the main reasons behind its limited power conversion efficiency. This has led to shifting of research focus on broadening the light absorption range of DSSCs, which can further lead to enhancement in overall power conversion efficiency. TiO2, doped with rare‐earth (RE) ions, is often used as an electron transport layer (ETL) in DSSCs to overcome this absorption‐related issue. This article gives a detailed review of TiO2 doped with different RE ions, as an electron transport layer in DSSCs. More importantly, we have summarized all the recent important findings with the application of DSSCs in LIB and photocapacitors.

Design and optical characterisation of an efficient light trapping structure for dye-sensitized solar cell integrated windows

Windows integrated with semi-transparent photovoltaics (PVs) such as Dye-Sensitized Solar Cells (DSSCs) show good potential in improving building performance, in terms of providing daylight, reducing unnecessary solar heat gain and also generating electricity onsite. However, low cell efficiency remains an obstacle for their applications in windows. Using light trapping structures in DSSCs shows the potential to improve solar to electrical conversion efficiency. In this work, different pyramid-patterned titanium dioxide (TiO2) geometries are designed to enhance the photon absorption in DSSCs, and characterised using a Monte-Carlo algorithm based 3D ray-tracing simulation. Various studies were carried out under average irradiation, spectrum dependent irradiation and different solar incidental angles, respectively. The simulation results at the average irradiation wavelength (540 nm) were compared to those from a previous study using Scanning Photocurrent Microscopy (SPCM) and a reasonable agreement has been achieved. It was found that the structure based on the pyramid array of side wall angle 54.7° can significantly enhance light absorption by up to ~25% and the maximum achievable photocurrent density (MAPD) by up to ~45% across the spectrum of 380–800 nm, when compared to a planar control counterpart.

Enhancement of dye sensitized solar cell efficiency through introducing concurrent upconversion/downconversion core/shell nanoparticles as spectral converters

Extending the spectral absorption of dye-sensitized solar cells from the visible into near-infrared and ultra-violet range enables the minimization of non-absorption loss of solar photons. Here, we report a viable strategy to implement simultaneously near-infrared upconversion and ultra-violet downconversion for dye-sensitized solar cells through constructing a type of upconversion-core/downconversion-shell-structured nanoparticles. For the first time, NaYF4:20%Yb,2%Er@NaYF4:7%Eu core/shell nanoparticles are applied to TiO2 photoanode for fabricating near-infrared/ultra-violet-enabled dye-sensitized solar cell devices. The incorporation of designed nanoparticles into TiO2 photoanode of dye-sensitized solar cells achieves high efficiency of 7.664% under one sun illumination, increasing the power conversion efficiency by about 13.95%. We confirm that the enhancement of overall efficiency includes 4.82% upconversion contribution, 7.58% downconversion function and 1.55% scattering effect. Our strategy opens the path for further broadening the solar spectral use to improve the performance of photovoltaic devices.

Efficient azobenzene co-sensitizer for wide spectral absorption of dye-sensitized solar cells.

Two azobenzene dyes, [Cu(azobenzene-4,4′-dicarboxylate) diethylenediamine]n (ADD), [Cd(4,4′-diazenediyldibenzoato)(H2O)]n (DDB), have been designed, synthesized, and characterized as efficient co-sensitizers for dye-sensitized solar cells (DSSC). The optical, charge-transfer, electrochemical and photovoltaic properties of ADD and DDB are investigated by UV-visible spectroscopy, transient surface photovoltage measurement, cyclic voltammetry, and photocurrent–photovoltage measurement. The combination of ADD and DDB in DSSC leads to a wide spectral absorption over the whole visible range (350–700 nm). DSSC with ADD and DDB exhibits a short-circuit photocurrent density as high as 16.96 mA cm−2, open-circuit photovoltage of 0.73 V, a fill factor of 0.57, and overall light conversion efficiency of 7.1% under standard global AM1.5 solar irradiation conditions.

Molecular Engineering of Near Infrared Absorbing Thienopyrazine Double Donor Double Acceptor Organic Dyes for Dye-Sensitized Solar Cells.

The thienopyrazine (TPz) building block allows for NIR photon absorption in dye-sensitized solar cells (DSCs) when used as a π-bridge. We synthesized and characterized 7 organic sensitizers employing thienopyrazine (TPz) as a π-bridge in a double donor, double acceptor organic dye design. Donor groups are varied based on electron donating strength and sterics at the donor-π bridge bond with the acceptor groups varied as either carboxylic acids or benzoic acids on the π-bridge. This dye design was found to be remarkably tunable with solution absorption onsets ranging from 750 to near 1000 nm. Interestingly, the solution absorption measurements do not accurately approximate the dye absorption on TiO2 films with up to a 250 nm blue-shift of the dye absorption onset on TiO2. This shift in absorption and the effect on electron transfer properties is investigated via computational analysis, time-correlated single photon counting studies, and transient absorption spectroscopy. Structure-performance relationships were analyzed for the dyes in DSC devices with the highest performance observed at 17.6 mA/cm2 of photocurrent and 7.5% PCE for a cosensitized device with a panchromatic IPCE onset of 800 nm.

Increased Light Absorption in Dye-Sensitized Solar Cells with Light Harvesting Dye

In plants, photosynthetic protein, light harvesting complexes (LHC), holds reaction center called photosystem I or II (PSI or PSII). PSI and PSII receive light energy and convert it to electric flow. This reaction is done in high quantum efficiency. This light-harvesting system enables the plants to use the sun-light efficiently. The converted electron is spatially transferred in multiple chemical steps, and this is called Z scheme. The Z scheme is known to be highly efficient which have nearly no loss of electric energy. Dye-sensitized solar cells (DSSCs) have attracted increasing attention because of its multiple advantages such as low-cost, lightweight, and flexibility. In DSSCs, photogenerated charge carriers in dye are separated and the electrons are injected to conduction band of semiconductor. The charge separating process of DSSCs is similar to that of photosynthesis. Here, we report DSSCs further imitated photosynthesis. The DSSCs we reported have applied the light-harvesting system in photosynthesis. Perylene-based fluorophore was dispersed in electrolyte in order to imitate the roll of chlorophyll, the light harvesting dyes, in nature. This material was chosen due to the high stability against photo-oxidation. Phthalocyanine, the sensitizing dye, was adsorbed on the surface of photoanode to convert photoenergy into an electric flow. The two synthetic dyes are selected to imitate the light-harvesting complex and reaction center, respectively. The energy absorbed at the fluorophore undergoes Förster resonant energy transfer (FRET) to the sensitizing dye. This allows broader spectral absorption, which is beneficial as a characteristic of a solar cell. We have fabricated the above-mentioned imitated system using synthetic dyes, and evaluated its performances on FRET and following electron transfer. Experiments were done as follows. Perylene-based fluorophore was dispersed in iodine/triiodide electrolytes. Three types of fluorophores with different emission wavelengths were used, and electrolytes with different fluorophore concentrations were prepared at the purpose of comparison. Two phthalocyanine-based sensitizing dyes, PcS2 and PcS20 (structures shown in Figure1 a and b), were chosen to investigate the impact of modifications around the main structure. Absorption characteristics of the two materials are nearly the same [1]. The TiO2electrode consisted of a 10 µm nanoporous layer with 3 µm scattering layer was prepared by screen printing. Solar cells were assembled using Surlyn film with platinized counter electrode. The electrolyte solution was introduced through two holes predrilled in the counter electrode. Evaluation of the samples was done using incident-photon-to-current conversion efficiency (IPCE). Figure 2 shows IPCE result of the solar cell using one of the three fluorophore and PcS2. As a result, the DSSCs fabricated using fluorophore with emission well matching the absorption of the sensitizing dye had shown a notable photo-electric conversion around 400-600 nm. The overall photovoltaic performance was greater than the case of no use of fluorophore at all. The solar cells with other two types of fluorophores had not shown this characteristic. Since the emission band of these two fluorophores does not match the adsorption band of the sensitizing dye, it is suggested that FRET reaction is involved in the trend seen in Fig. 2. In conclusions, DSSCs with plant-inspired structure was fabricated and their photovoltaic performance was investigated. Occurrence of FRET among the fluorophore introduced in the electrolyte and the sensitizing dye was suggested from the comparison between the evaluation using fluorophores with different emission band. Synthetizing dyes with different modification had shown the difference, in which suggests that the bulkiness of the dye affects the reaction in the photoanode surface. The overall photovoltaic performance was shown to improve by creating a structure that induces FRET reaction. Ref.1 S. Mori, M. Nagata, Y. Nakahata, K. Yasuta, R. Goto, M. Kimura, and M. Taya J. Am. Chem. Soc. 2010, 132, 4054-4055 Figure 1

Aggregates of plasmonic nanoparticles for broadband light trapping in dye-sensitized solar cells

Metallic nanoparticles (NPs) have not been effective in improving the overall performance of the cells with micrometer-thick absorbing layers mainly due to the parasitic optical dissipation in the metal. Here, using both experiment and theory, we demonstrate that aggregates of metallic NPs enhance the light absorption of dye-sensitized solar cells of a few micrometer-thick light absorbing layers. The composite electrode containing the optimal concentration of 5 wt% Au@SiO2 aggregates shows the enhancement of 80% and 52% in external quantum efficiency and photocurrent density, respectively. The superior performance of the aggregates relative to NP is attributed to their larger scattering efficiency using full-wave optical simulations. This is further confirmed by optical spectroscopic measurements showing that a large fraction of the incident light couples into the diffused components because of the presence of these metallic aggregates. The optical absorption enhancement is broadband and it is particularly strong at wavelengths larger than 680 nm where the optical absorption of dye molecules is weak.

Solar power generation enhancement of dye-sensitized solar cells using hydrophobic and antireflective polymers with nanoholes

A negatively tapered nanohole-patterned polydimethylsiloxane (PDMS) antireflective protection layer with a hydrophobic surface improves the sunlight absorption of dye-sensitized solar cells.

Aluminum plasmonic nanoparticles enhanced dye sensitized solar cells.

We present an investigation on utilizing plasmonic aluminium (Al) nanoparticles (NPs) to enhance the optical absorption of dye-sensitized solar cells (DSCs). The Al NPs exhibit not only the light absorption enhancement in solar cells with localized surface plasmon (LSP) effect but also the chemical stability to iodide/triiodide electrolyte. Besides, the lower work function (~4.06 eV), compared with that of TiO₂ (~4.6 eV), may suppress the quenching processes, such as charge transfer to metal NPs, to reduce the loss. Thus, high concentration of Al NPs could be incorporated into the TiO₂ anodes, and the power conversion efficiency (PCE) of DSCs is improved by nearly 13%. Moreover, electrochemical impedance spectroscopy (EIS) characterization also indicates that the plasmonic DSCs with Al NPs present better electrochemical performance than regular ones, which contributes to the improvement of PCE of the device.

Nanosilver‐Decorated TiO2 Nanofibers Coated with a SiO2 Layer for Enhanced Light Scattering and Localized Surface Plasmons in Dye‐Sensitized Solar Cells

Enhanced harvesting of visible light is vital to the development of highly efficient dye-sensitized solar cells (DSSCs). Nanosilver-decorated TiO2 nanofibers (Ag@TiO2 NFs) were synthesized by depositing chemically reduced Ag ions onto the surface of electrospun TiO2 nanofibers (TiO2 NFs). The prepared Ag@TiO2 NFs were coated with SiO2 (SiO2@Ag@TiO2 NFs) by using PVP as coupling agent for protecting corrosion of Ag nanoparticle by I(-)/I3(-) solution. The fabricated SiO2@Ag@TiO2 NFs demonstrated a synergistic effect of light scattering and surface plasmons, leading to an enhanced light absorption. Moreover, an anode consisting of SiO2@Ag@TiO2 NFs incorporating TiO2 nanoparticles (NPs) increased light harvesting without substantially sacrificing dye attachment. The power conversion efficiency increased from 6.8 to 8.7 % for a thick film (10 μm), that is, 28 %. These results suggest that SiO2@Ag@TiO2 NFs are promising materials for enhanced light absorption in dye-sensitized solar cells.

Plasmonic Enhancement of Dye-Sensitized Solar Cells Using Core–Shell–Shell Nanostructures

We report the synthesis of core−shell−shell Au@SiO2@TiO2 nanostructures and demonstrate near-field plasmonic enhancement of dye-sensitized solar cells (DSSCs) incorporating them. Isolated nanoparticles as well as nano- structured plasmonic aggregates with broadband light absorption throughout the visible light region are developed. Comparisons to theoretical calculations are performed for the nanoparticles to provide further insight into their structure. We show that Au@SiO2@TiO2 nanoparticles provide efficiency enhancements greater than that of Au@SiO2 plasmonic nanoparticles and vary the distance between the molecular chromophore and the gold NP surface to demonstrate that this arises from near-field plasmonic effects. Finally, enhancement of dye absorption in DSSCs using a coupled plasmonic system is shown for the first time and results in a broadband enhancement of quantum efficiency.

Plasmon-enhanced photocurrent in dye-sensitized solar cells

Plasmonic structures of FTO/TiO2/NPs-Ag and FTO/NPs-Ag/TiO2 electrodes were fabricated by sputter technology and the sol–gel & spin coating procedure. These electrodes with similar optical absorptions in the visible region enhanced by the surface plasmon resonance of silver nanoparticles have different photovoltaic properties, revealing that the significant design can be used to identify the favorably enhanced direction of plasmonic structure resulting from plasmonic scattering to trap light which confines light within the active TiO2 layer to promote dye absorption in dye-sensitized solar cells (DSSCs). In the FTO/TiO2/NPs-Ag, a 60% enhancement in photocurrent and an improvement in photovoltage were observed and the increased incident photon-to-photocurrent efficiency (IPCE) was consistent with the enhanced absorption spectrum. However, the photovoltaic properties of the FTO/NPs-Ag/TiO2 were similar to those of the standard electrode. This concept is potentially applicable to new kinds of solar cells.

Time-Evolution of Poly(3-Hexylthiophene) as an Energy Relay Dye in Dye-Sensitized Solar Cells

Energy relay dyes (ERD) and Förster resonant energy transfer (FRET) are useful techniques for increasing absorption in dye-sensitized solar cells. We use femtosecond transient absorption spectroscopy to monitor charge generation processes in a solid-state DSC containing poly(3-hexylthiophene) (P3HT) as both the hole-transporter and the ERD with a zinc phthalocyanine dye (TT1) as the sensitizer. We observe efficient FRET occurring on picosecond time scales and subsequent hole transfer from TT1 to P3HT occurring onward from 100 ps.