染料敏化太阳电池介孔薄膜电极的研究进展

介绍了染料敏化太阳电池多孔二氧化钛薄膜电极的结构、工作原理及其制备方法,并进一步阐述了减小电荷复合速率、改进薄膜电极性能、提高器件的光电转化效率的方法,主要涉及多孔二氧化钛薄膜电极的复合、掺杂和表面包覆等表面改性处理技术。指出了基于有序二氧化钛薄膜电极、柔性二氧化钛薄膜电极的染料敏化太阳电池和叠层薄膜结构的太阳电池高效的转化效率和应用方便的特点,并在此基础上展望了未来的研究方向。     

Non-vacuum deposition of CIGS absorber films for low-cost thin film solar cells

Thin film solar cells composed of chalcopyrite Cu(In_1?x Ga _x )(Se_1?y S _y )₂ (CIGSSe) absorbers have gained considerable attention in recent years in an effort to develop sustainable technologies for harnessing clean energy. Nonvacuum solution methods can reduce production costs by replacing vacuum-based deposition methods with large-scale, high-throughput processes. The efficient use of materials can reduce production costs. Non-vacuum processes generally rely on two sequential steps: solution-coating, followed by a post-annealing process. Depending on the point at which the CIGS phase evolves, non-vacuum processes can be categorized as nanoparticle (NP) approaches or molecular precursor approaches. These two types of liquid processes are believed to be compatible with a variety of applications, such as roll-to-roll coating for the production of flexible, portable devices. Additional thermal treatments using a gaseous chalcogen or oxygen can improve the absorber quality. This review describes the current status of chalcopyrite thin film solar cells fabrication methods via low-cost solution routes. An analysis of recently published reports describing liquid-based deposition methods is introduced, and the features of the development steps are compared. Finally, a discussion and future outlook are offered.     

Flexible CZTSSe thin film solar cells fabricated at low temperature with relieved residual stress by Sb incorporation

The troublesome residual stress is always a stumbling block that drags the progress pace of flexible CZTSSe thin film solar cells, which urgently needs to be noticed and solved. In this paper, low-temperature prepared CZTSSe absorber with relieved residual stress (0.558 GPa) is realized by Sb incorporation. Owing to the evaporated 20 nm Sb layer under CZTS precursor, the crystalline quality and band mismatching of CZTSSe/CdS interface are simultaneously improved. Additionally, the spatial potential fluctuation extracted from the PL results is found to decrease from 63.26 meV to 41.57 meV, indicating a reduction in band tailing and disorder of CZTSSe absorber. Compared with the general solar cells fabricated at 580 °C, flexible devices with Sb incorporation can maintain a slightly higher performance at a lower temperature about 60 °C. The best power conversion efficiency (PCE) of 4.41% is obtained in the solar cell with 550 °C-selenized CZTSSe absorber after incorporating 20 nm Sb layer, featuring 351.20 mV Voc, 25.73 mA/cm² Jsc and 48.79% FF. Finally, low-temperature prepared flexible CZTSSe thin film solar cell can retain over 83% of the original PCE after bending at 180° for 40 cycles. The mechanical durability paves a promising way for flexible CZTSSe thin film solar cell in roll-to-roll production.     

Manufacture of mullite substrates from andalusite for the development of thin film solar cells

The purpose of this work is the manufacture of dense thin mullite substrates by tape casting of the natural silicate mineral andalusite. The targeted application for such substrates is the manufacture of thin film solar cells. Indeed, in addition to a good resistance at high temperature (up to 1200 °C), this application requires a good correspondence between the thermal expansion coefficient of the substrate and silicon film in order to lower the stresses in the film and in the substrate after cooling. The work was performed in three successive stages. First, the study of the transformation during sintering of andalusite+alumina mixtures. Second, the optimisation of the slurries and of the parameters for tape casting. Finally, green tapes prepared from various powder compositions were characterised before and after sintering. The addition of alumina to andalusite reduces the final amount of vitreous phase. This limits the risk of impurity diffusion in the silicon film. However, the addition of alumina also slows down the sintering process leading to more porosity in the substrates. A good compromise is obtained with an initial mixture of 80 wt.% andalusite with 20 wt.% alumina. In that case, the thermal expansion behaviour is very close to pure mullite and the mechanical properties of the substrates can be considered as sufficient for the targeted application.     

Studies on chemical bath deposited SnS2 films for Cd-free thin film solar cells

Tin disulfide (SnS₂) is a simple binary metal chalcogenide and it has been proposed as a promising buffer material for Cd-free thin film solar cells. The present work explores the deposition of SnS₂ films by a facile chemical bath deposition at different deposition times in the range of 30–120 min. The effect of deposition time on the structural, optical and electrical properties was investigated. The as-grown SnS₂ films showed a hexagonal crystal structure with a high intensity (001) peak at 15.03°. The films showed shuttle shaped grains that were uniformly distributed across the surface of the substrate. The films showed an optical energy band gap in the range of 2.95–2.80 eV. PL spectra showed a strong emission peak in the wavelength range, 410–460 nm with the variation of deposition time. The SnS₂ films prepared at a deposition time of 90 min showed good crystallinity and morphology with low resistivity of 11.2 Ω-cm. A solar cell with device structure of Mo/SnS/SnS₂/i-ZnO/Al: ZnO/Ni/Ag was fabricated. The fabricated solar cell showed an efficiency of 0.91%, which validate the photovoltaic performance of SnS₂ films.     

Photo-thermal process on BiFeO3 thin film

This study demonstrates that a photo-thermal process, namely a concurrently light illumination during annealing, is an effective method to develop a high-quality BiFeO₃ (BFO) thin film. The wavelength-dependent light effect, which is determined by the photo absorption property of the sol-gel synthesized BFO solution, assisted in the decomposition of organic residues within the film during the thermal history. The photo absorption property of the BFO precursor varied with an exponential function of temperatures. By using a combination of an appropriate wavelength light illumination and a suitable temperature thermal annealing, the BFO film formed in a uniform dense microstructure with near-stoichiometric composition which was difficult to achieve with a traditional thermal process. We proposed the application of light illumination under thermal process would improve the reaction sequences of the constituent species as well as the crystallization mechanism of BFO, then providing the flexibility to control the film characteristics.     

汉高第三代薄膜前处理工艺的应用

总结了汉高第三代薄膜前处理技术的工艺和设备应用情况,对目前研究中存在的问题和难点提出了解决思路,展望了今后的研究方向.     

Effect of compressed TiO2 nanoparticle thin film thickness on the performance of dye-sensitized solar cells

In this study, dye-sensitized solar cells (DSSCs) were fabricated using nanocrystalline titanium dioxide (TiO₂) nanoparticles as photoanode. Photoanode thin films were prepared by doctor blading method with 420 kg/cm² of mechanical compression process and heat treatment in the air at 500°C for 30 min. The optimal thickness of the TiO₂ NP photoanode is 26.6 μm with an efficiency of 9.01% under AM 1.5G illumination at 100 mW/cm². The efficiency is around two times higher than that of conventional DSSCs with an uncompressed photoanode. The open-circuit voltage of DSSCs decreases as the thickness increases. One DSSC (sample D) has the highest conversion efficiency while it has the maximum short-circuit current density. The results indicate that the short-circuit current density is a compromise between two conflict factors: enlargement of the surface area by increasing photoanode thickness and extension of the electron diffusion length to the electrode as the thickness increases.     

Profound optical analysis for novel amorphous Cu2FeSnS4 thin films as an absorber layer for thin film solar cells

In this study, quaternary kesterite Cu₂FeSnS₄ (CFTS₄) has been selected due to its interesting optical and electrical characteristics. The CFTS₄ films were prepared by exploiting the chemical bath deposition process at room temperature. The films were prepared at different deposition periods (1, 3, 5 and 7 h). The EDAX technique was helped in evaluating the compositional element ratio which near to 2:1:1:4. The morphology and structure of CFTS₄ films have been examined by utilizing X-ray diffraction, and field emission scanning electron microscope techniques. XRD charts revealed the absence of sharp peaks and approved the amorphous nature of films under investigations. The transmittance and reflectance data were employed to compute the linear and nonlinear optical constants of the as-deposited CFTS₄ films. The energy gap calculations for the CFTS₄ films grown on glass substrate displayed a direct energy gap and by increasing the deposition time, a reduction in energy gap values from 1.41 to 1.19 eV was obtained. The deep analysis of linear/nonlinear optical properties as a function of deposition time has revealed many characteristics of the investigated films. Moreover, the nonlinear parameters (refractive index n₂, nonlinear absorption coefficient β_c and the third-order nonlinear optical susceptibility χ⁽³⁾) of the CFTS₄ films were boosted with rising up the film thickness and their high values imply the possibility of utilizing these films in various optoelectronic applications.     

Analysis of process peculiarities of thin film disalination plants

In this article a large complex of researches on hydrodynamics and heat transfer is carried out on a current of thin film in up flow, down flow and horizontal-tube falling film desalination plants. Based on the results of observation of the mode of movement of a film on such heating surfaces and steam formation, explanations of physical features of hydrodynamics are given, and heat transfer for seawater and their essential difference in relation to distillate is shown. By results of data processing the currents, ensuring stability, minimal charge of seawater are offered for these processes, as well as an equation for calculation of average and maximal thickness of a film. The equations of heat transfer characteristics for all these thin film regimes are obtained.     

Recast Nafion‐117 thin film from water solution

Perfluorosulfonated ionomer (PFSI) dispersions in various solvents, usually mixtures of organic compounds and water, were used to prepare the membrane‐electrode system in polymer electrolyte membrane fuel cells (PEMFC), the aim being to increase performance by improving the triple contact of graphite (electron conducting material), Pt (hydrogen dissociation catalyst) and ionomeric membrane (proton conducting). When using PFSI dispersions in water‐organic solvent mixture, care must be taken not to poison the Pt catalyst through organic decomposition products, a consequence of the thermal treatment of the electrode‐polymer system bonded with PFSI dispersion. In the present study some procedures for preparing Nafion water dispersion, starting from a Nafion‐117 membrane, are described. The morphological characteristics of the prepared dispersions were compared with Nafion commercial dispersion (NCD). Moreover, membranes with a thickness of 5–20 μm were prepared and characterised, using both the obtained and the NCD dispersions. The obtained data showed that Nafion water dispersion, which can be used to prepare the membrane/electrode system, results in thin membranes that absorb more water than NCD membranes, and have equal and/or higher proton conduction than the NCD.     

Fabrication of thin film nanocrystalline TiO2 solar cells using ruthenium complexes with carboxyl and sulfonyl groups

Two ruthenium complexes with carboxyl and sulfonyl groups have been synthesized, [Ru^II(L1)₂(NCS)₂] Ru^IIbis(4,7-diphenyl-1,10-phenanthroline-disulfonic acid disodium salt)-di(thiocyanate) [K313], [Ru^II(L1)₂(dcbpy)] Ru^II bis(4,7-diphenyl-1,10-phenanthroline-disulfonic acid disodium salt)(4,4′-dicarboxy-2,2′-bipyridyl) [K314] as photosensitizers. UV–vis, fluorescence emission, AFM and CV measurements are also supplied for ruthenium complexes. Photovoltaic properties of dye sensitized nanocrystalline semiconductor solar cells based on Ruthenium complexes which bear carboxyl and sunfonyl groups have been tested under standard AM 1.5 sunlight. Under the standard global AM 1.5 solar conditions, K314 and K313-sensitized solar cells demonstrate short circuit photocurrent densities of 14.92 mA/cm² and 11.23 mA/cm² and overall conversion efficiencies of 5.09% and 4.02%, respectively.     

Incorporation of carbon nanotube into direct-patternable ZnO thin film formed by photochemical solution deposition

Direct-patterning of ZnO hybrid films containing MWNT was realized without using photoresist and dry etching. Photosensitive 2-nitrobenzaldehyde was introduced into the solution precursors as a stabilizer and contributed to form a cross-linked network structure during photochemical reaction. According to the incorporation of multi-walled nanotube (MWNT) into ZnO films, the transmittance of ZnO hybrid film containing MWNT did not change but the sheet resistance was improved due to the enhancement of charge mobility due to π-bonding nature of MWNT. These results suggested a possibility that a micro-patterned system can be fabricated relatively easily and without high-cost processes, for example, by conventional etching procedure.     

Properties and mechanism of solar absorber CdTe thin film synthesis by unipolar galvanic pulsed electrodeposition

Electrochemical deposition of CdTe semiconductor thin films over transparent conducting glass substrates by sequential unipolar current pulses is described. The magnitude of pulsed current and pulse periodicity affects the crystalline structure, morphology, optical absorbance and composition of CdTe films. CdTe films formed under high magnitude pulsed current density ~5–15 mA cm⁻² are crystalline with dominant cubic structure having (111) plane oriented parallel to the substrate. Stoichiometric CdTe film growth occurs with current pulses of short 25–300 ms periodicity and 3–50 ms duration. A mechanism of the CdTe growth involving in situ cathodic tellurization process step involving H₂Te formation and reaction with electrochemically deposited Cd monolayer is described. CdTe film growth in the pulsed electrodeposition occurs under mass transport conditions under strong influence of high magnitude pulsed current. This results in much higher growth rates ~5–8 μm h⁻¹ for CdTe films which is attractive for CdTe solar cells in a production environment.     

Dynamics and control of thin film surface microstructure in a complex deposition process

In this work, a complex deposition process, which includes two types of macromolecules whose growth behaviors are very different, is investigated. This deposition process is influenced by both short- and long-range interactions. The study of this process is motivated by recent experimental results on the growth of high-κ dielectric thin films using plasma-enhanced chemical vapor deposition. A multi-component kinetic Monte-Carlo (kMC) model is developed for the deposition. Both single- and multi-component cases are simulated and the dependence of the surface microstructure of the thin film, such as island size and surface roughness, on substrate temperature and gas phase composition is studied. The surface morphology is found to be strongly influenced by these two factors and growth regimes governed by short- and long-range interactions are observed. Furthermore, two kMC model-based feedback control schemes which use the substrate temperature to control the final surface roughness of the thin film are proposed. The closed-loop simulation results demonstrate that robust deposition with controlled thin film surface roughness can be achieved under a kMC estimator-based proportional integral (PI) feedback controller in the short-range interaction dominated growth regime, while a kMC model-predictive controller is needed to control the surface roughness in the long-range interaction dominated growth regime.     

PET薄膜在太阳能电池背板上的应用

介绍PET薄膜在太阳能电池背板上的应用。该薄膜的厚度一般为250μm,主要是具有水气阻隔性、电气绝缘性、尺寸稳定性、易加工性及耐撕裂等功能。用于背板上的PET薄膜性能比普通PET薄膜的要更好些。     

Polycarbazole obtained by electrochemical polymerization of monomers either in solution or in thin film form

Polycarbazole has been synthesized by electrochemistry. The carbazole monomer source consists either in carbazole in solution in the electrolyte or in carbazole deposited in thin film form onto the working electrode. The two families of polymers have been studied by infrared absorption, X‐ray diffraction, thermal gravimetric analysis, scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy, electron spin resonance, and electrical conductivity measurements. It is shown that the polycarbazole films obtained with carbazole deposited in the thin film form exhibit a better polymerization efficiency and an electrical conductivity one order of magnitude higher. This result is in good accordance with a higher spin density and homogeneity. It is proposed that not only are some monomers activated during the evaporation but also that the physical contact between the working electrode and the continuous carbazole films induces the growth of homogenous highly polymerized polycarbazole films. In agreement with this suggestion, the SEM study shows that this type of polycarbazole thin films keep in memory the morphology of the SnO₂ under layer. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1561–1568, 2000     

Ignition of a thin film by a beam of radiant energy

The problem of destruction of a thin polymer film due to heating by a beam of radiant energy is studied. The multistage nature of chemical conversion and dependence of optical properties on depth of decomposition is considered. Analytical estimates are given for the time characteristics of film ignition and its dependence on beam thickness and heating intensity. Optical phenomena related to the chemical reactions are observed by a numerical method.Tomsk. Translated from Fizika Goreniya i Vzryva, Vol. 27, No. 6, pp. 3–10, November–December, 1991.