应用于染料敏化太阳电池的TiO2纳米复合电解质材料

研究了以凝胶电解质和无机纳米复合电解质取代液态电解质，在保持体系电导率的同时，增强对溶剂的保持能力，提高DSCs的稳定性。以自由基聚合法制备了聚（4-乙烯基吡啶）作为骨架，通过化学交联制备了具有三维网络结构的凝胶电解质体系，并与TiO2纳米粉末复合制备了有机．无机纳米复合电解质体系。利用FTIR、交流阻抗、差热分析等方法对纳米复合电解质体系进行了分析与表征。制备了纳米复合材料作为电解质的准固态染料敏化太阳电池，并测定了电池的光电性能。结果表明：化学交联法制备的凝胶电解质和纳米复合电解质均具有与液态电解质相当的电导率，而其对电解质溶剂的保持能力相对于液态电解质体系有所提高：复合电解质体系中的TiO2纳米颗粒既可以作为体系的骨架，又提高了体系的热稳定性。以纳米复合电解质制备的DSC光电转换效率达到了3．3％（1cm^2有效面积，100mW／cm^2光强）。     

Preparation and characterization of TiO2 photoelectrode codoped with aluminum and boron and its application in dye-sensitized solar cell

Nanocrystalline titania films codoped with aluminum and boron were prepared by cathodic vacuum arc deposition. In the process, titanium alloy target was used under an O2/Ar atmosphere, and sensitization of films were carried out by natural dye-sensitized complex in anhydrous ethanol. The structure, surface morphology and UV-vis spectra of titania films codoped were measured by X-ray diffraction analysis, scanning electron microscopy and ultraviolet-visible spectrometer. Theas-deposited films are found to be amorphous. The films annealed were examinedto be of anatase structure with orientation along the (101) planes, the averagecrystal size is in the range between 41 and 45 nm. SEM results show that thereare some pores in the codoped titania films, the optical properties of the dye-sensitized films were also measured which reveals that the spectral responses of films shift to the visible region. Under simulated sunlight illumination, the overall energy conversion efficiency of dye-sensitized nanocrystalline solar cell is 0.9%.     

Organic photosensitizers with N-carboxymethyl pyridinium acceptor/anchoring group for dye-sensitized solar cells

Four new organic dyes with N-carboxymethyl pyridinium as electron acceptors/anchoring groups were designed and synthesized. The optical and electrochemical properties were characterized by UV–vis, fluorescence spectroscopy and cyclic voltammetry. The absorption spectra of the four pyridinium dyes were in the range of 450–650 nm. The dye with triphenylamine as the electron donor shows a solar-energy-to-electricity conversion efficiency (η) of 2.33% in comparison with the reference Ru-complex (N719 dye) with a η value of 5.45% under the same experimental conditions. The dye with phenoxazine as the electron donor gives broad IPCE spectra in the range of 400–750 nm. All these new dyes are simple in structure, very easy to synthesize, and gives high V_oc.     

Facile synthesis of ZnO nanobullets/nanoflakes and their applications to dye-sensitized solar cells

In this paper we reported a successful synthesis of ZnO nanobullets/nanoflakes by a simple hydro/solvothermal method employing a mixture of water/ethylene glycol as the solvent, and zinc acetate as the zinc source. The final products were characterized by powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Raman scattering and photofluorescence spectra of the products were also investigated. ZnO with both nanobullets and nanoflakes nanostructures had been comparably studied as active photoanodes in dye-sensitized solar cell (DSSC) system, and the overall light-to-energy conversion efficiency of 1.93% has been achieved for nanobullets based DSSC, while that for ZnO nanoflakes based DSSC has been raised up to 3.64%.     

Effect of polyethyleneimine on the growth of ZnO nanorod arrays and their application in dye-sensitized solar cells

A series of oriented hexagonal wurtzite ZnO nanorod-array films were grown on fluorine-doped tin oxide (FTO) coated glass substrates by chemical process. The effect of polyethyleneimine (PEI) on the structure and micro-morphology of ZnO nanorod array films, as well as the photoelectric conversion properties in dye-sensitized solar cells (DSSCs) was analyzed. It was found that with the addition of PEI in growth solution, the ZnO nanorods became smaller in diameter and longer in length and hence the dye absorption and the photovoltaic performance of DSSCs were improved. A power conversion efficiency of 2.30% had been achieved on a DSSC based on a 7.9 μm-long nanorod array film prepared by a growth solution containing the PEI.     

Modification of poly(ethylene oxide) electrolyte by Brönsted base terminated oligo(ethylene glycol) and its application in dye-sensitized solar cells

Oligo(ethylene glycol) terminated by pyridine derivatives was designed and synthesized for improving the performance of the dye-sensitized solar cells (DSCs) with poly(ethylene oxide) based electrolyte. Effects of the plasticizer on retarding the recombination reaction in DSCs were characterized by current density–voltage characteristics. Combined with the results on electron density measurements, photovoltage–intensity characteristics correlate the retarded electron recombination with the upward movement of the conduction band edge and the reduced order of recombination reaction. The increased electron lifetimes of the DSCs with plasticizer modified electrolyte were confirmed by a small perturbation voltage decay technique. Additionally, WAXS measurements show that the presence of the plasticizer decreases the crystallinity of PEO electrolyte, which facilitates the mass transport of the redox species as impedance spectra indicated. By introducing guanidinium thiocyanate into the plasticizer modified PEO electrolyte, the performance of the DSCs is further improved, which yields the highest efficiency of 3.5%.     

Mesoporous (N, S)-codoped TiO2 nanoparticles as effective photoanode for dye-sensitized solar cells

(N, S)-codoped titania (TiO₂) is synthesized by a simple template-free solvothermal method as photoanode for dye-sensitized solar cells (DSSCs). The results confirm that N and S have been doped into the lattice of anatase, which can enhance the visible-light absorbance and promote the electron transportation in TiO₂. The prepared (N, S)-codoped TiO₂ exhibits pure anatase phase mesoporous nanoparticles with average diameter of 60 nm. Mixing (N, S)-codoped TiO₂ with Degussa P25 as photoanode results in the improvement of open-circuit voltage and short-circuit photocurrent density of DSSC. And the corresponding DSSC obtains a high conversion efficiency of 8.0%.     

Influence of TiCl4 treatment on performance of dye-sensitized solar cell assembled with nano-TiO2 coating deposited by vacuum cold spraying

Titanium tetrachloride (TiCl4) treatment was employed to TiO2 coating deposited on fluoride-doped tin oxide (FTO) conducting glass and indium oxide doped tin oxide (ITO) conducting glass, respectively. The nano-crystalline TiO2coating was deposited using a composite powder composed of polyethylene glycol (PEG) and 25 nm TiO2 particles by vacuum cold spraying (VCS) process. A commercial N-719 dye was used to adsorb on the surface of TiO2 coating to prepare TiO2 electrode, which was applied to assemble dye-sensitized solar cell (DSC).The cell performance was measured under simulated solar light at an intensity of 100 mW·cm-2.Results show that with an FTO substrate the DSC composed of a VCS TiO2 electrode untreated by TiCl4 gives a short-circuit current density of 13.1 mA·cm-2 and an open circuit voltage of 0.60 V corresponding to an overall conversion efficiency of 4.4%. It is found that after TiCl4 treatment to the VCSTiO2 electrode with an FTO substrate, the short circuit current density of the cell increases by 31%, the open-circuit voltage increases by 60 mV and a higher conversion yield of 6.5% was obtained. However, when an ITOsubstrate is used to deposit TiO2 coating by VCS, after TiCl4 treatment, the conversion efficiency of the assembled cell reduces slightly due to corrosionof the conducting layer on the ITO glass by TiCl4.     

Influences of magnesium particles incorporated on electrophoretically multiwall carbon nanotube film on dye-sensitized solar cell performance

Multiwall carbon nanotube (MWCNT) films are prepared on a conductive substrate by electrophoretic deposition. The thickness of MWCNT films is found to increase with the carbon nanotube concentration and the deposition duration. Scanning electron microscopy and energy dispersive X-ray measurements detect magnesium particles incorporated on the MWCNT films. The performance of dye-sensitized solar cell using the electrophoretically MWCNT films as a counter electrode shows a relationship dependent on the film thickness and the amount of magnesium loading. The increase in the magnesium loading on carbon films diminishes the solar cell efficiency. This is because magnesium particles cover the carbon nanotube surface reducing the nanotube catalytic sites and blocking electron transfer to tri-iodide (I₃⁻) ions.     

Co-sensitization with near-IR absorbing cyanine dye to improve photoelectric conversion of dye-sensitized solar cells

Two carboxylated cyanine dyes, 3-butyl-2-[3-(1-butyl-5-carboxy-1,3-dihydro-3,3-dimethyl-2H-indol-2-ylidene)-1-propen-1-yl]-1,1-dimethyl-7-[1-[2-[6-(4-morpholinyl)-1,3-dioxo-1H-benz[de]isoquinolin-2(3H)-yl]ethyl]-1H-1,2,3-triazol-4-yl]-1H-Benz[e]indolium iodide (A), 2-[5-(1-butyl-5-carboxy-1,3-dihydro-3,3-dimethyl-2H-indol-2-ylidene)-1,3-pentadienyl]-3-ethyl-1,1-dimethyl-1H-Benz[e]indolium iodide (B), have been prepared and their photophysical and electrochemical properties have been investigated. A, B and their mixtures (AB) were used as sensitizers in nanocrystalline TiO₂ solar cells to improve photoelectric conversion efficiency. It was found that the solar cell sensitized with A3B1 (molar ratio: A:B = 3:1) generated a high power conversion efficiency of 3.0% under AM1.5G illumination (100 mW cm⁻²), indicating that co-sensitization is a promising method to improve the photoelectrical properties of dye-sensitized solar cells.     

Strategy to Improve the Performance of Dye-sensitized Solar Cells Based on TiO2 Films Prepared by Room Temperature Cold Spray

Dye-sensitized solar cells(DSCs)are promising photochemical solar cells owing to their high efficiency and low cost.In this study,the influence of cell geometry,electrolyte composition,and counter electrode(CE)characteristics on the performance of DSCs was investigated to aim at improving the cell efficiency.Using an U-type cell geometry proposed decreased the internal resistance of DSCs and therefore increased the fill factor and energy conversion efficiency.The addition of DMPII to the I-/I3-based electrolyte increased the open-circuit voltage by decreasing the dark current.Compared to the DSCs with the Pt CE prepared by the thermal decomposition of H2PtCl6,the DSCs with the sputtered Pt CE showed a higher fill factor and short-circuit current density,owing to the high electrical conductivity and enhanced light-reflecting ability of the mirror-like sputtered Pt CE.Based on these results,the energy conversion efficiency of the DSC with the TiO2 porous films fabricated by a room temperature cold spray method was increased from 3.93%to 5.11%.The relatively high efficiency shows that the room temperature cold spray is a prospective method in fabricating nanocrystalline TiO2 films for flexible DSCs.     

钙钛矿太阳能电池稳定性的研究进展

回顾了钙钛矿太阳能电池的发展历程,总结了影响钙钛矿太阳能电池稳定性的几个重要因素,包括水汽、氧气、光照和高温条件对钙钛矿层的化学稳定性以及电子传输层(ETL)、空穴传输层(HTL)和制备工艺对电池稳定性的影响。对稳定机制进行了分析,提出了改善稳定性的一些方法,并根据目前的研究成果展望了钙钛矿太阳能电池的发展趋势。     

Charge transport and recombination in dye-sensitized solar cells based on hybrid films of TiO2 particles/TiO2 nanotubes

In this paper, anodic TiO₂ nanotubes are blended into the TiO₂ mesoporous films based on P25 nanoparticles to assemble a list of dye-sensitized solar cells (DSSCs) with different nanotube concentrations. The electron properties of transport and recombination in the fabricated DSSCs are studied by using electrochemical impedance spectroscopy and the open-circuit voltage decay technique under AM 1.5 illumination. Results indicate that the electron lifetime increases with increasing the concentration of the anodic TiO₂ nanotubes, the electron transport time at a blending level of 10 wt% TiO₂ nanotubes is short as compared to that at 0 wt%, and above 10 wt%, the electron transport time has a trend of becoming large. Due to the combining effects of the electron transport and recombination, the electron collecting efficiency and the electron diffusion length obtain maxima at a blending level of 10 wt% nanotubes, which results in a highest short circuit current and a maximum energy conversion efficiency at this point in the DSSCs. This study gives a clear explanation for the performance enhancement of TiO₂ particle-based DSSCs at a blending level of 10 wt% anodic TiO₂ nanotubes and for the performance decrease at a blending level over 10 wt% anodic TiO₂ nanotubes from the angle of the electron transport and recombination. This study also supplies a feasible and easy way to improve the performance of particle-based DSSCs by restraining electron recombination and accelerating electron transportation.     

Research progress in electron transport layer in perovskite solar cells

Since perovskite solar cells appeared in 2009, its simple preparation process, high photoelectric conversion efficiency and the characteristic of low cost in preparation process let it become the hot spot of both at-home and abroad. Owing to the constant efforts of scientists, the conversion efficiency of perovskite solar cells is more than 20% now. Perovskite solar cells are mainly composed of conductive glass, electron transport layer and hole transport layer, perovskite layer and electrode parts. This paper will briefly introduce the working principle and working process about the electron transport layer of perovskite solar cells. The paper focuses on aspects such as material types(e.g., inorganic electron transport materials, organic small molecule electron transport materials, surface modified electron transport materials and doped electron transport materials), preparation technology of electron transport layer, the effects of electron transport layer on the photovoltaic performance of the devices, and the electron transport layer in the future research.     

An optimized multilayer structure of CdS layer for CdTe solar cells application

CdS layers grown by ‘dry’ (close space sublimation) and ‘wet’ (chemical bath deposition) methods are deposited and analyzed. CdS prepared with close space sublimation (CSS) has better crystal quality, electrical and optical properties than that prepared with chemical bath deposition (CBD). The performance of CdTe solar cell based on the CSS CdS layer has higher efficiency than that based on CBD CdS layer. However, the CSS CdS suffers from the pinholes. And consequently it is necessary to prepare a 150 nm thin film for CdTe/CdS solar cell. To improve the performance of CdS/CdTe solar cells, a thin multilayer structure of CdS layer (∼80 nm) is applied, which is composed of a bottom layer (CSS CdS) and a top layer (CBD CdS). That bi-layer film can allow more photons to pass through it and significantly improve the short circuit current of the CdS/CdTe solar cells.     

The double-edged function of UV light in polymer solar cells with an inverted structure

Inverted polymer solar cells with a configuration of ITO/ZnO/PBDTTT-C:PC₇₁BM/MoO₃/Ag were fabricated and a power conversion efficiency of 6.64% was achieved under AM 1.5G irradiation (89 mW/cm²). The function of UV light was systematically investigated by tracking the changes of the device performance for 212 min under continuous illumination with or without UV light. We found that UV light plays a decisive role not only in the photo-annealing step, leading to a remarkable increase of PCE by increasing ZnO conductance, but also in the photo-bleaching step, causing slow degradation of solar cells through photo-oxidation of the conjugated polymer.     

A novel microwave absorption and dielectric spectrum detection technology in photoelectron dynamic study for solar cells

The photoelectron property is directly related to the light-energy conversion efficiency of solar cells. In this paper, the photoelectron dynamic of semiconductor was analyzed. The diffusion of electrons has influence on the dielectric function of the solar cell material. And the amplitude variance of the imaginary andreal part of the dielectric function is in direct proportion to the dynamic process of free and shallow-trapped electrons. Based on the untouched detection technique, the method is present to detect the amplitude change of the microwave signal which is passing through the material whose dielectric function changes after exposure. A35GHz oscillator was used as a microwave source. The absorptionand dispersion microwave signals, which contain the dynamic information of free and shallow-trapped electron signal, are split respectively with phase-sensitive instrument. The photoelectron character of n-type Si(100) thin film was investigated by the novel equipment, and the lifetime of different kinds of electronswith the resolution of 1 ns was obtained. The equipment can be directly used inthe study of the optoelectronic conversion mechanism of solar cells.     

Role of PbO-based glass frit in Ag thick-film contact formation for crystalline Si solar cells

The reactions between Ag pastes containing two types of PbO-based glass frits and an n-type (100) Si wafer during firing in air at 800 °C were investigated in order to understand the mechanism for the formation of inverted pyramidal Ag crystallites at the Si interface as well as the effect of the PbO content of the glass frit on Ag crystallite formation. Inverted pyramidal Ag crystallites were formed by the precipitation of Ag atoms dissolved in fluidized glass during the subsequent cooling process after firing. PbO in the glass frit did not participate directly in the reaction with the Si wafer. However, its content had a strong influence on the reaction rate at the glass/Si interface and, thus, on the size and distribution of the Ag crystallites. The effect of the PbO content in the glass could be understood from the higher Ag solubility and lower viscosity of the glass at the firing temperature with increasing PbO content. Based on the experimental results, a model was proposed for the formation of Ag crystallites at the glass/Si interface during the firing process of screen-printed thick-film Ag metallization.     

Spray deposition of CuInS2 on electrodeposited ZnO for low-cost solar cells

CuInS₂ (CIS) thin films are deposited using chemical spray pyrolysis on top of a single (compact) and a double (compact + porous) ZnO film obtained by electrodeposition by changing the composition, pH and temperature of the bath. Conductive glass has been used as primary substrate. CIS films are deposited at 300 °C and using N₂ as carrier. A buffer layer of TiO₂ is incorporated by spray to protect the ZnO layer against dissolution during the subsequent spraying of CIS. Relevant properties, such as morphology, composition and thickness are evaluated using SEM, EDX and XRD. Also, UV-Vis analyses are carried out to assess the band gap value of CIS, resulting in 1.42 eV. Carrier densities and flat band potentials (V_fb) are calculated from Mott-Schottky plots. The values of V_fb are 0.70, 1.10 and 0.42 V for TiO₂, ZnO and CIS respectively. I-V curves in the dark and under illumination prove that the materials can be combined to obtain solar cells. The dark response for the two devices built with single and double layers of ZnO is very similar, showing diode behavior with good rectification ratios. Under illumination, the presence of the porous ZnO improves the performance of the cell, as reflected by the higher values of photocurrent and open circuit potential.