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1.
The effects of TiO2 photoelectrode's surface morphology and different solvents on the photovoltaic performance of dye-sensitized solar cells (DSSCs) were studied. By successive coating of TiO2 suspension, composed of low and high molecular weight poly(ethylene)glycol (PEG) as a binder, double layered TiO2 photoelectrodes with four different structures were obtained. Among the DSSCs with different TiO2 electrodes, DSSC with P2P1 electrode (P2 and P1 correspond to PEG molecular weights of 20,000 and 200,000, respectively) showed higher performance under identical film thickness at a constant irradiation of 100 mW cm−2, which may be correlated with large pore size and high surface area of the corresponding TiO2 electrode. This was confirmed by electrochemical impedance spectroscopy (EIS) analysis of the DSSC and the transient photovoltage measurement of electrons in the TiO2 electrode. Among the different solvents investigated here, the DSSC containing acetonitrile showed high conversion efficiency and the order of performance of the DSSCs with different solvents were AN > MPN > PC > GBL > DMA > DMF > DMSO. Better correlation was observed between the donor number of solvents and photoelectrochemical parameters of the DSSCs containing different solvents rather than the measured viscosity and dielectric constant of solvents. The reasons for the low performance of the DSSCs containing DMA, DMSO and DMF, respectively, were due to the negative shift of TiO2 conduction band and the desorption of dye molecules from the TiO2 photoelectrode by those solvents. 相似文献
2.
Photo-electrochemical solar cells based on a core-shell structure including ZnO shell and TiO2 cove, have been fabricated with ruthenium bipyridyl complex (N719) as the sensitizer. Compared with the pure anatase TiO2, the ZnO-covered TiO2 film possesses outstanding ability to transport electrons with an overall power conversion efficiency of 3.72. Elctrochemical
study shows that surface modification of TiO2 film with ZnO can increase the concentration of free electrons in the conduction band of TiO2. This remit implies that the charge recombination is reduced in process of electron transport through the TiO2 porous film, which can decrease the photocurrent loss and hence improve Dye-Sensitized solar ceils (DSSCs) efficiency. This
result indicates that optimization of TiO2 porous network fabrication condition is efficient, for the improvement of TiO2 based DSSC’s performances. 相似文献
3.
This study employs chlorophyll extract from pomegranate leaf and anthocyanin extract from mulberry fruit as the natural dyes for a dye-sensitized solar cell (DSSC). A self-developed nanofluid synthesis system is employed to prepare TiO2 nanofluid with an average particle size of 25 nm. Electrophoresis deposition was performed to deposit TiO2 nanoparticles on the indium tin oxide (ITO) conductive glass, forming a TiO2 thin film with the thickness of 11 μm. Furthermore, this TiO2 thin film was sintered at 450 °C to enhance the thin film compactness. Sputtering was used to prepare counter electrode by depositing Pt thin film on FTO glass at a thickness of 20 nm. The electrodes, electrolyte (), and dyes were assembled into a cell module and illuminated by a light source simulating AM 1.5 with a light strength of 100 mW/cm2 to measure the photoelectric conversion efficiency of the prepared DSSCs. According to experimental results, the conversion efficiency of the DSSCs prepared by chlorophyll dyes from pomegranate leaf extract is 0.597%, with open-circuit voltage (VOC) of 0.56 V, short-circuit current density (JSC) of 2.05 mA/cm2, and fill factor (FF) of 0.52. The conversion efficiency of the DSSCs prepared by anthocyanin dyes from mulberry extract is 0.548%, with VOC of 0.555 V and JSC of 1.89 mA/cm2 and FF of 0.53. The conversion efficiency is 0.722% for chlorophyll and anthocyanin as the dye mixture, with VOC of 0.53 V, JSC of 2.8 mA/cm2, and FF of 0.49. 相似文献
4.
This research coats a commercial TiO2 nanoparticle Degussa P25 with good roundness and size uniformity on an indium tin oxide (ITO) glass substrate and to be photoelectrical electrode by electrophoresis deposition. It combined with dye N719, electrolyte I-/ and counter-electrode of Pt layer to produce dye-sensitized solar cells (DSSCs). Through the electrophoretic technique, a multilayer film of an appropriate thickness is deposited in the suspension containing TiO2 nanoparticles and isopropanol. In this process, electric current, voltage, and the number of deposition cycles are well controlled to obtain a single TiO2 film of around 3.3 μm thick. Stacking is then performed to obtain a multilayer-typed TiO2 film of around 12 μm thick. As the sintering temperature reaches 400 °C, the prepared multilayer TiO2 film with a good compactness can increase the dye adsorption capability of the thin film and enhance its adsorption percentage. In addition, the heat treatment will transfer a portion of the rutile crystalline into the anatase crystalline, resulting in better material properties for DSSCs application. DSSCs produced are exposed to metal halide lamp and their energy conversion efficiency is measured. The I-V curve of the produced DSSCs shows that it has an excellent energy conversion efficiency of 6.9%. 相似文献
5.
Dye-sensitized solar cells (DSSCs) comprising randomly networked titanium nanoparticles usually exhibit lower energy conversion efficiency and limited electron mobility due to the scattering and trapping of free electrons. In this study, attempts were made to improve the electron mobility in DSSCs using vertically aligned and well ordered TiO2 nanotubes. These nanotubes were prepared by the electrochemical etching of Ti foil under potentiostatic conditions in four different fluorinated organic solvents under varying anodizing conditions like reaction time, and annealing before/after anodization. Sonoelectrochemistry was found to be more effective to synthesize well-ordered TiO2 nanotubes than just stirring the electrolyte as in conventional electrochemistry. Using NH4F-EG as an anodizing electrolyte, unique TiO2 nanomorphology with longer nanotubes length of 18 μm was achieved. The photo-electrochemical properties of the DSSCs with back illumination under UV (<400 nm) and simulated sunlight (AM 1.5) were also studied, and exhibited an efficiency of 2.13%. The results are reported in detail here. 相似文献
6.
Dye-sensitized solar cells (DSSCs) incorporating TiO2 porous films, prepared at a low temperature (150 °C), along with multi-wall carbon nanotubes (MWCNTs) were studied using two different electrolytes, namely LiI and THI. Electrochemical impedance spectroscopy (EIS) was employed to quantify the charge transport resistance and electron lifetime (τe) under different levels (wt%) of MWCNTs and electrolytes. The charge transport resistance at the TiO2/dye/electrolyte interface (Rct2) increased as a function of the MWCNT concentration, which ranged 0.1-0.5 wt%, due to a decrease in the surface area and decreased dye adsorption. The characteristic peak shifted to a lower frequency at 0.1 wt% of MWCNT, indicating a longer electron lifetime. The DSSC with the TiO2 electrode containing 0.1 wt% of MWCNT resulted in a higher short-circuited current density (JSC) of 9.08 mA/cm2, an open-circuit voltage (VOC) of 0.781 V, and a cell conversion efficiency of 5.02%. EIS was also conducted under dark conditions. The large value at a middle frequency represented electron transport at the TiO2/dye/electrolyte interface (Rrec). The Rrec for 0.1 wt% MWCNT/TiO2 was found to be 114 Ω, and for those with 0.3 and 0.5 wt% were 35 and 30 Ω, respectively. The significantly higher value of Rrec suggested that the charge recombination between injected electrons and electron acceptors in the redox electrolyte, I3−, was remarkably retarded. Finally, electrolytes with LiI and THI were used to compare the cell conversion performance under the same conditions. It was found that more electrons were injected in the TiO2 electrode and the electron recombination reaction was faster in the DSSC with THI than that with LiI. 相似文献
7.
Youngsoo Kim Beom Jin Yoo R. Vittal Yeonhee Lee Nam-Gyu Park Kang-Jin Kim 《Journal of power sources》2008
The effects of low-temperature O2 plasma treatment of a TiO2 film are studied with the objective of improving the performance of dye-sensitized solar cells (DSSCs). X-ray photoelectron spectra (XPS) reveal that the ratio of titanium dioxide to titanium sub-oxides is increased in the O2 plasma-treated TiO2 film, compared with that of the untreated TiO2 film. This increase suggests that the oxygen vacancies in the film are effectively reduced. The near-edge X-ray absorption fine structure (NEXAFS) spectra results agree with the XPS result. It is proposed that there is a correlation between the shifts of the peaks in the NEXAFS spectra and the adsorption of N719 dye on the TiO2 particles. A DSSC having an O2 plasma-treated, 4 μm thick TiO2 film electrode renders a short-circuit photocurrent of 7.59 mA cm−2, compared with 6.53 mA cm−2 for a reference cell with an untreated TiO2 electrode of the same thickness. As a result of these changes, the solar-to-electricity conversion efficiency of the O2 plasma-treated cell is found to be 4.0% as compared with 3.5% for the untreated cell. This improvement in the performance is rationalized on the basis of increased N719 dye adsorption on to the TiO2, due to the reduction in the number of oxygen vacancies caused by the oxygen plasma treatment. 相似文献
8.
Yumin Liu Xiaohua Sun Qidong Tai Hao Hu Bolei Chen Niu Huang Bobby Sebo Xing-zhong Zhao 《Journal of power sources》2011,196(1):475-481
A novel and thin ZnO compact blocking film is employed at the interface of fluorine-doped tin oxide (FTO) substrate and mesoporous TiO2, and its influence on dye-sensitized solar cells (DSSCs) is investigated. The ZnO film prepared by spin-coating method on FTO is characterized by energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and UV–vis spectrophotometer. The ZnO film is firstly employed as an energy barrier between FTO and mesoporous TiO2 film in DSSCs, which improves open-circuit photovoltage (Voc) and fill factor (FF) with compensation of Jsc decrease, finally increasing energy conversion efficiency from 5.85% to 6.70%. Electrochemical impedance spectra (EIS) analysis and open-circuit voltage decay (OCVD) technique reveal that the existence of the energy barrier not only resulted in the effect of suppressing back electrons transfer from FTO to electrolyte but also blocking the electrons injection from the conductive band of TiO2 to FTO. The former effect effectively reduces the recombination which occurs in the region of FTO substrate, and the latter leads to remarkable increment of electron density in the TiO2, thus resulting in enhanced Voc and FF. These results suggest that the methodology of introducing the semiconductor with a more negative conduction band edge than TiO2 as the compact blocking film in DSSCs may be feasible. 相似文献
9.
Ying Yang Hao HuCong-Hua Zhou Sheng XuBobby Sebo Xing-Zhong Zhao 《Journal of power sources》2011,196(4):2410-2415
Quasi-solid state dye-sensitized solar cells (DSSCs) are fabricated with a novel polysaccharide gel electrolyte composed of agarose in 1-methyl-2-pyrrolidinone (NMP) as polymer matrix, lithium iodide (LiI)/iodine (I2) as redox couple and titania nanoparticles as fillers. The polysaccharide electrolyte with different agarose concentrations (1-5 wt%) and various inorganic filler TiO2 concentrations (0-10 wt%) are studied systematically by differential scanning calorimetry (DSC) and the AC impedance spectra. The electrochemical and photoelectric performances of DSSCs with these electrolytes are also investigated. It is found that increasing agarose and inorganic filler concentration leads to a decrease in Tg in the range of 1-2 wt% for agarose and 0-2.5 wt% for TiO2 changed electrolytes, which results in high conductivity in these electrolytes. From the electrochemical analysis, it is observed that the electron lifetime in TiO2 of DSSCs increases with agarose, while decreases with inorganic filler contents. The prolonged electron lifetime in DSSCs is advantageous to improve open-circuit voltage (Voc). Based on these results, the cell with the electrolyte of 2 wt% agarose shows the optimized energy conversion efficiency of 4.14%. The optimized efficiency of the DSSC with added titania is 4.74% at 2.5 wt% titania concentration. 相似文献
10.
Jian-Ging Chen Shi-Jhang Wu Chun-Guey Wu Kuo-Chuan Ho 《Solar Energy Materials & Solar Cells》2008,92(12):1723-1727
In this study, the photoelectrochemical characteristics of a ruthenium photosensitizer with an alkyl bithiophene group, designated as CYC-B1, are studied. The effect of mesoporous TiO2 film thickness on the photovoltaic performance of CYC-B1 and N3 dye-sensitized solar cells was investigated. The performance of the dye-sensitized nanocrystalline TiO2 solar cells (DSSC) fabricated using CYC-B1 dye-anchored TiO2 photoelectrode showed a convincing enhancement in cell efficiency when the TiO2 film thickness was increased from 3 μm (eff.=5.41%) to 6 μm (eff.=7.19%). The efficiency of the CYC-B1-sensitized DSSC was maximum at 6 μm of the TiO2 film thickness, reached its limiting value and remained constant up to 53 μm, although a similar trend was also observed for N3 dye-sensitized DSSC, however, the maximum efficiency achieved was only at 27 μm thickness (eff.=6.75%). As expected, the photocurrent density generated in the DSSC modified by CYC-B1 dye is larger than that from N3 dye. The effect of guanidinium thiocyanate (GuSCN) (additive) addition to the electrolyte on the photovoltaic performance of DSSCs based on CYC-B1 was also investigated. Furthermore, the electrochemical impedance spectroscopy (EIS) technique and photo-transient laser method have been employed to analyze the charge transfer resistances (Rct) and the lifetime of the injected electrons on the TiO2 containing different thicknesses. 相似文献
11.
Soon Hyung Kang Moon-Sung Kang Hyun-Sik Kim Jae-Yup Kim Young-Hoon Chung William H. Smyrl Yung-Eun Sung 《Journal of power sources》2008
Columnar-structured rutile TiO2 film with a thickness of 1.4 μm is prepared using the radio-frequency (RF) magnetron sputtering technique, for application in dye-sensitized solar cells (DSSCs). Pure rutile TiO2 films are fabricated by controlling the substrate temperature during sputtering and using a substrate with a rough surface morphology. Successive substrate heating to 623 K induces the growth of a rutile TiO2 film that has a specific direction in the (1 1 0) plane, which results in a decrease in the average grain size. This causes in an increase of dye uptake and thereby contributes to enhancement of the photocurrent in the DSSC. 相似文献
12.
Tae Kwan YunSung Soo Park Duckhyun KimYong-Kyung Hwang Seong HuhJae Young Bae Yong Sun Won 《Journal of power sources》2011,196(7):3678-3682
The effect of the pore size of mesoporous anatase-TiO2 on the photovoltaic performance of dye-sensitized solar cells (DSSCs) is investigated. The mesoporous TiO2 particles are synthesized by two different methods using a soft template of tri-block copolymer and a hard template of mesoporous ZnO/Zn(OH)2-composite. These methods produce the same high surface area (SBET ∼ 210 m2 g−1) but different pore sizes of 6.8 and 3.0 nm, respectively. With the mesoporous TiO2 having larger pores, the photo-conversion efficiency (η) is increased significantly to 6.71%, compared with 5.62% that is typically achieved using P25 TiO2 nanopowders. By comparison, only half the performance (3.05%) has been observed with mesoporous TiO2 that has small pores. Mesoporous TiO2 with suitable pore sizes (∼6.8 nm) makes the most of its high surface area and thereby allows a high uptake of dye to enhance the current density. In contrast, the low efficiency of mesoporous TiO2 with small pores is attributed to the low uptake of dye due to the smaller pore size (∼3.0 nm), which blocks the diffusion and adsorption of dye molecules through the pores. 相似文献
13.
Dye-sensitized solar cells (DSSCs) based on anatase TiO2 hollow spheres (TiO2HS)/multi-walled carbon nanotubes (CNT) nanocomposite films are prepared by a directly mechanical mixing and doctor blade method. The prepared samples are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-vis absorption spectroscopy and N2 adsorption-desorption isotherms. The photoelectric conversion performances of the DSSCs based on TiO2HS/CNT composite film electrodes are also compared with commercial-grade Degussa P25 TiO2 nanoparticles (P25)/CNT composite solar cells at the same film thickness. The results indicate that the photoelectric conversion efficiencies (η) of the TiO2HS/CNT composite DSSCs are dependent on CNT loading in the electrodes. A small amount of CNT clearly enhances DSSC efficiency, while excessive CNT loading significantly lowers their performance. The former is because CNT enhance the transport of electrons from the films to FTO substrates. The latter is due to high CNT loading shielding the visible light from being adsorbed by dyes. 相似文献
14.
Sujuan Wu Hongwei HanQidong Tai Jing ZhangSheng Xu Conghua ZhouYing Yang Hao HuBoLei Chen Xing-zhong Zhao 《Journal of power sources》2008
A novel surface modification method was carried out by reactive dc magnetron sputtering to fabricate TiO2 electrodes coated with Al2O3 for improving the performance of dye-sensitized solar cells (DSSCs). The Al2O3-coated TiO2 electrodes had been characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), UV–vis spectrophotometer, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The study results revealed that the modification to TiO2 increases dye absorption amount, reduces trap sites on TiO2, and suppresses interfacial recombination. The impact of sputtering time on photoelectric performance of DSSCs was investigated. Sputtering Al2O3 for 4 min on 5-μm thick TiO2 greatly improves all cell parameters, resulting in enhancing the conversion efficiency from 3.93% to 5.91%. Further increasing sputtering time decreases conversion efficiency. 相似文献
15.
M.K. ParvezI. In J.M. ParkS.H. Lee S.R. Kim 《Solar Energy Materials & Solar Cells》2011,95(1):318-322
UV photo-crosslinkable polymer electrolytes based on poly(ethylene glycol) (PEG) and poly(ethylene glycol) diacrylate (PEGDA) were used in dye-sensitized solar cells (DSSCs). PEG and bifunctional PEGDA formed a crosslinked structure upon UV light illumination, confirmed by the solubility test and FTIR spectroscopy. The polymeric electrolyte was prepared by photo-polymerization after injecting the monomer electrolyte solution into the porous film in order to make close contact with the TiO2 porous film. Under AM 1.5 (100 mW/cm2) light irradiation for up to 20 min, a maximum 62% increase in the photo-conversion efficiency (η%) was observed. The DSSCs with the crosslinkable PEG/PEGDA based polymer electrolyte showed improved long-term stability in comparison to those with electrolytes containing only PEG. Also, the effects of solvent on stability of the DSSCs were investigated. 相似文献
16.
Triphenylamine- and benzothiadiazole-based dyes with multiple acceptors for application in dye-sensitized solar cells 总被引:1,自引:0,他引:1
Two novel dyes TPAR3 and BTDR2 based on triphenylamine and benzothiadiazole, respectively, with multiple electron acceptors were synthesized and characterized by FT-IR, 1H NMR, TGA and thermomechanical analysis (TMA). They carried terminal cyanoacrylic acid electron acceptors/anchoring moieties, which were connected with the central unit through a thiophene ring. The absorption bands of the dyes were extended up to ∼570 nm with long-wave absorption maximum at 425-455 nm and optical band gap of 2.10-2.17 eV. The dyes emitted yellow-orange light with photoluminescence maximum at 547-615 nm. We have investigated the photovoltaic properties of quasi solid state dye sensitized solar cells (DSSCs) based on these metal free organic dyes. It has been found that the power conversion efficiency of the DSSCs based on composite zinc titanium oxide (ZTO) nanocrystalline photoelectrode is higher than that for TiO2 based DSSCs. This has been attributed to the longer electron lifetime and more negative conduction band edge of ZTO. The overall power conversion efficiency of the DSSCs based on TPAR3 and BTDR2 employing ZTO photoelectrode is 6.3% and 3.6%, respectively. These results indicate that both the acceptor moiety of metal free organic dyes and ZTO photoelectrode have an effect on the photovoltaic performance of DSSCs. 相似文献
17.
A densely packed TiO2 thin film onto an indium doped–tin oxide (ITO) substrate was synthesized at room temperature by chemical deposition and a CdS thin film was deposited onto the pre-deposited TiO2 film by a doctor blade route (powder of CdS was obtained from chemical deposition). TiO2/CdS film was annealed at 300 °C for 1 h in air for crystallinity improvement. The first grown TiO2 film was nanocrystalline, whereas the CdS film was polycrystalline as evidenced by X-ray diffraction (XRD) and selected area electron diffraction (SAED). Scanning electron microscopy (SEM) images show formation of mono-dispersed CdS spherical grains onto compact, densely packed spherical nanocrystalline grains of TiO2. The TiO2/CdS bilayer film was used in a photo-electrochemical cell as a working electrode, and a platinum electrode as a counter electrode (0.1 M lithium iodide electrolyte) under 80 mW/cm2 light illumination intensity. 相似文献
18.
This study measures the diffusion coefficients of I− and I3− in oligomer electrolytes as a function of the molecular weight of oligomers and investigates their effect on the performance of dye-sensitized solar cells (DSSCs). The high-diffusion coefficients of ions in an oligomer electrolyte with a lower molecular weight can help to promote the redox mechanism in DSSCs and thereby increase the short-circuit current density. They can also cause a decrease in the open-circuit voltage since a high-diffusion coefficient of I3− is capable of reducing the lifetime of electrons in TiO2 electrodes. To offset these effects, N-methyl-benzimidazole is added to the oligomer electrolytes, thereby improving the open-circuit voltage and fill factor and, consequently, the overall energy-conversion efficiency, which increases to over 5%. A further test involving storage at a high temperature of 75 °C demonstrates that DSSCs employing the oligomer electrolytes show excellent thermal stability over 200 h. 相似文献
19.
Jin-A JeongHan-Ki Kim 《Solar Energy Materials & Solar Cells》2011,95(1):344-348
We report on the characteristics of a TiO2 passivating layer grown by radio frequency (RF) magnetron sputtering on F-doped SnO2 (FTO) electrodes as a function of its thickness. The optical transparency, surface roughness and passivation properties of the TiO2 layer passivating the FTO electrode depend on the thickness of the TiO2 passivating layer. In addition, it was found that the power conversion efficiency of the dye-sensitized solar cells (DSSCs) is critically dependent on the thickness of RF sputtered TiO2 layer inserted between FTO electrode and nanoporous TiO2 layer. The DSSC fabricated on 50 nm thick TiO2 passivating FTO electrode showed the maximum power conversion efficiency of 4.42% due to effective prevention of the electron transfer to electrolyte. This indicates that the thickness optimization of the TiO2 passivating layer is one of the important parameter to obtain high performance DSSCs. 相似文献
20.
Cauliflower-like TiO2 rough spheres, which are about 200 nm large, have greatly enhanced light harvesting efficiency and energy conversion efficiency of dye-sensitized solar cells (DSC), due to their high light scattering effect and large BET surface area (80.7 m2 g−1) even after calcinations at 450 °C for 30 min. The large size TiO2 rough and smooth spheres, produced at different initial temperatures by hydrolysis of Ti(OBu)4 with P105 (EO37PO56EO37) or F68 (EO78PO30EO78) tri-block copolymer as structural agents, have nearly the same diameter of ∼275 nm and strong light scattering effects in the wavelength of 400–750 nm. However, rough spheres have even higher light scattering effect and larger BET surface area than smooth spheres for the roughness of the surface. By adding 25 wt.% large TiO2 spheres into the over-layer of TiO2 film composed of ∼20 nm TiO2 particles as light scattering centers, the energy conversion efficiency of the film containing rough spheres reaches 7.36%, much larger than that of smooth spheres (6.25%). From another point of view, the TiO2 rough spheres may have the satisfying ability in other fields of application such as photo-catalysis, drug carriers and so on. 相似文献