硅基薄膜太阳能电池 工艺技术的改进和现场维护 激光环节的工艺流程及其条件

第一篇：硅基薄膜太阳能电池 工艺技术的改进和现场维护 激光环节的工艺流程及其条件

Optimization of microcrystalline silicon thin film solar cell isolation processing parameters using ultraviolet laser

Optics & Laser Technology This study used ultraviolet laser to perform the microcrystalline silicon thin film solar cell isolation scribing process, and applied the Taguchi method and an L18 orthogonal array to plan the experiment.The isolation scribing materials included ZnO:Al, AZO transparent conductive film with a thickness of 200 nm, microcrystalline silicon thin film at 38% crystallinity and of thickness of 500 nm, and the aluminum back contact layer with a thickness of 300 nm.The main objective was to ensure the success of isolation scribing.After laser scribing isolation, using the minimum scribing line width, the flattest trough bottom, and the minimum processing edge surface bumps as the quality characteristics, this study performed main effect analysis and applied the ANOVA(analysis of variance)theory of the Taguchi method to identify the single quality optimal parameter.It then employed the hierarchical structure of the AHP(analytic hierarchy process)theory to establish the positive contrast matrix.After consistency verification, global weight calculation, and priority sequencing, the optimal multi-attribute parameters were obtained.Finally, the experimental results were verified by a Taguchi confirmation experiment and confidence interval calculation.The minimum scribing line width of AZO(200 nm)was 45.6 μm, the minimum scribing line width of the microcrystalline silicon(at 38% crystallinity)was 50.63 μm and the minimum line width of the aluminum thin film(300 nm)was 30.96 μm.The confirmation experiment results were within the 95% confidence interval, verifying that using ultraviolet laser in the isolation scribing process for microcrystalline silicon thin film solar cell has high reproducibility.Fabrication of thin film silicon solar cells on plastic substrate by very high frequency PECVD Fabrication of thin film silicon solar cells on plastic substrate by very high frequency PECVD

Solar Energy Materials and Solar Cells

The paper describes the way to transfer process technology of state-of-the-art high efficiency thin film silicon solar cells fabrication on cheap plastic(such as PET or PEN)substrates, by two completely different approaches:(i)by transfer process(Helianthos concept)of thin film silicon cells deposited at high substrate temperature, Ts(at low Ts（200 °C)and(ii)direct deposition on temperature sensitive substrates 100 °C).Adaptation of the process parameters and cell processing to the requirement of the flexible/plastic substrate is the most crucial step.In-situ diagnosis of the plasma has been done to understand the effect of inter-electrode distance, substrate temperature and hydrogen dilution on the gas phase conditions.Whereas, for the transfer process, the inter-electrode distance is a critical deposition condition that needs to be adapted for the flexible substrates, the direct deposition on plastic substrates has an added issue of loss in material quality and the deposition rate due to depositions at low Ts.Our studies indicate that ion energy is crucial for obtaining compact films at low temperature and high hydrogen dilution helps to compensate the loss of ion energy at low substrate temperatures.Efficiencies of 5.9% and 6.2% have been obtained for n–i–p type a-Si cells on PET and PEN substrates, respectively, using direct deposition.Using an adapted inter-electrode distance, an a-Si/nc-Si tandem cell on plastic(polyester)substrate with an efficiency of 8.1% has been made by Helianthos cell transfer process.Large-size multi-crystalline silicon solar cells with honeycomb textured surface and point-contacted rear toward industrial production

In this paper, we present a multi-crystalline solar cell with hexagonally aligned hemispherical concaves, which is known as honeycomb textured structure, for an anti-reflecting structure.The emitter and the rear surface were passivated by silicon nitride, which is known as passivated emitter and rear(PERC)structure.The texture was fabricated by laser-patterning of silicon nitride film on a wafer and wet chemical etching of the wafer beneath the silicon nitride film through the patterned holes.This process succeeded in substituting the lithographic process usually used for fabricating honeycomb textured structure in small area.After the texturing process, solar cells were fabricated by utilizing conventional fabrication techniques, i.e.phosphorus diffusion in tube furnace, deposition of anti-reflection film and rear passivation film by chemical vapor deposition, front and rear electrodes formation by screen printing, and contact formation by furnace.By adding relatively small complicating process to conventional production process, conversion efficiency of 19.1% was achieved with mc-Si solar cells of over 200 cm in size.The efficiency was independently confirmed by National Institute of Advanced Industrial Science and Technology(AIST).2Recent advances in very high frequency plasma enhanced CVD process for the fabrication of thin film silicon solar cells Thin Solid Films

We have deposited amorphous silicon(a-Si)and nanocrystalline silicon(nc-Si)materials and the total p–i–n configurations for solar cells in a high vacuum multichamber system ASTER using very high frequency plasma enhanced chemical vapour deposition(VHF PECVD)process.The deposition process is monitored and controlled by in-situ diagnostic tools to maintain reproducibility of the material quality.In this paper we show our recent results on single junction(amorphous silicon)and tandem(a-Si/nc-Si)cells on plastic foil using the Helianthos concept.The tandem cell efficiency on Asahi U-type SnO2:F coated glass is ~ 12% and this is achieved by employing nc-Si deposited at high pressure(p)conditions of 5 mbar and a small inter-electrode distance(d)of 5 mm.The deposition scheme of this cell on glass was adapted for the SnO2:F coated Al foil substrates from Helianthos b.v., especially taking into account the expansion of the foil during deposition.The inter-electrode distance d was one of the variables for this optimisation process.Depositions at four inter-electrode distances of 6 mm, 8 mm, 10 mm and 12 mm(keeping the pressure–distance product constant)revealed that the deposition rate increases at higher distances, reaching 0.6 nm/s at a d of 10 mm and pressure p of 3.0 mbar.The Raman crystalline ratio showed a monotonic increase with the combination of higher d and lower p.Tandem cells with an area of 2.5 cm on plastic foil fabricated by the Helianthos concept and employing the above mentioned nc-Si made at 0.6 nm/s in the bottom cell and a-Si in the top cell, showed an efficiency of 8.12%, with a short circuit current density of 10 mA/cm.The combined deposition time of the photoactive silicon layers of the top and bottom cells amounted to only 85 min.Transparent conducting oxide layers for thin film silicon solar cells

Texture etching of ZnO:1%Al layers using diluted HCl solution provides excellent TCOs with crater type surface features for the front contact of superstrate type of thin film silicon solar cells.The texture etched ZnO:Al definitely gives superior performance than Asahi SnO2:F TCO in case of nanocrystalline silicon(nc-Si)type of solar cells.The stress of the ZnO:Al film changes from tensile to compressive with the increase in substrate temperature of sputter deposition and the rms roughness and the haze of the film seem to have a correlation with the stress of the film prior to etching;the sample made at 150 °C is most tensile and the etching rate and the evolved roughness is least at this condition whereas the sample made at 350 °C with a compressive stress character gives a high roughness.At present the ZnO:Al made at room temperature provides the best combination of the electrical property and the scattering property of the texture etched layer.A current density of

mA/cm has been obtained for a nc-Si cell

2of 2200 nm thick.To apply such a texturing technique to make rough ZnO:Al TCO layers on PET and PEN substrates for solar cells on plastics, an additional step of embossing the plastics prior to the sputter deposition of the ZnO:Al layers was employed to release the undue stress.The texture etching of such layers on plastics showed excellent scattering properties in addition to the good electrical properties.As far as ZnO:Al as back reflector is concerned, use of a thick, low doped ZnO:Al in combination with white reflectors, instead of metals, will be a possible solution to avoid surface plasmon absorption loss.We have successfully applied this concept using 0.5% Al doped ZnO to a superstrate type a-Si solar cell using upconversion material at the back of the solar cell.In case of substrate type solar cells on plastics, the ZnO:Al layers that are used as the Ag/ZnO:Al back reflector as well as barrier layers, have to be thin and made at a low stress condition.Such a process resulted in on PET and PEN substrates.6% efficiency of n-i-p a-Si solar cells Spatially distributed model for the analysis of laser beam induced current(LBIC)measurements of thin film silicon solar modules

激光束引介的薄型硅基太阳能膜的生产方式分析 ： 三维分布式工艺模块的处理模型

A 3D distributed model is developed and implemented based on circuit analysis software for the investigation of spatial variation in performance due to the distributed nature and non-uniformity of solar cell properties.This is applied to LBIC measurements where it is used for sensitivity analysis of the measurements with respect to certain parameters in series connected thin film PV modules.The model is used to explain the differences in dark and illuminated measurements, which clearly shows the illuminated LBIC signal is largely dependent on the homogeneity of the background illumination.The dark LBIC is largely affected by the shunt resistance of the neighbouring cells rather than by the signal strength of the cell under test.It is required to bring the cell into limiting conditions, which then gives a signal one order of magnitude stronger than that in the non-limiting case.The simulations are validated against measurements taken in these regimes.Development of a rapid thermal annealing process for polycrystalline silicon thin-film solar cells on glass 太阳能玻璃

Materials Science and Engineering

In this report, we discuss the influence of rapid thermal annealing(RTA)on the performance of polycrystalline Si(poly-Si)thin-film solar cells on glass where the poly-Si layers are differently prepared.The first part presents a comprehensive study of RTA treatments on poly-Si thin-films made by solid phase crystallization(SPC)(standard material of CSG Solar AG, Thalheim).By varying both plateau temperature(up to 1050 °C)and duration(up to 1000 s)of the annealing profile, we determined the parameters for a maximum open-circuit voltage(VOC).In addition, we applied our standard plasma hydrogenation treatment in order to passivate the remaining intra-grain defects and grain boundaries by atomic hydrogen resulting in a further increase of VOC.We found, that the preceding RTA treatment increases the effect of hydrogenation already at comparable low RTA temperatures.The effect on hydrogenation increases significantly with RTA temperature.In a second step we investigated the effect of the RTA and hydrogenation on large-grained poly-Si films based on the epitaxial thickening of poly-Si seed layers.Optimization of the p–i interface properties in thin film microcrystalline silicon solar cell

太阳能薄膜电池的成分优化配比设计

Solar Energy Materials and Solar Cells Hydrogenated microcrystalline silicon(μc-Si:H)has become attractive for use in thin-film silicon solar cells.The external quantum efficiency(EQE)of μc-Si:H solar cells extends up to 1100 nm, which is exploited in tandem solar cells.Properties of p–i interface are critical for performance as it affects carrier collection, which is visible in the blue response.Here, we report how μc-Si:H p-and i-layer material properties influence the p–i interface of μc-Si:H solar cells.The effect of RF PECVD parameters of these layers on the p–i interface was investigated.We find that the blue response of the solar cell is sensitive to the crystallinity of both the p-and i-layers.We demonstrate that transient depletion during i-layer deposition affects the blue response of μc-Si:H solar cell.We obtained a narrow process window for optimal solar-cell performance.At the optimal deposition pressure of 9 mbar and using transient depletion, an EQE at 400 nm of 0.6 was obtained, achieving 16% higher short-circuit current density.Reducing the diborane flow during p-layer deposition yielded 13% relative increase in efficiency.Epitaxially grown emitters for thin film silicon solar cells result in 16% efficiency Thin Solid Films

Epitaxial thin film silicon solar cell technology is one of the most promising midterm alternatives for cost effective industrial solar cell manufacturing.Here, CVD is used to grow the active base layer.However, also the emitter can be grown by CVD, with doping profiles as desired.In this paper, solar cell processes are established integrating both a two-step CVD grown emitter, and state-of-the-art concepts for optical light trapping in epitaxial cells.In this way, the significant increase in Voc is combined with an improved short-circuit and leads to a record efficiency of 16.1% with a current density of 33.2 mA/cm, approaching the Jsc of bulk silicon solar cells.2

Back surface reflectors with periodic textures fabricated by self-ordering process for light trapping in thin-film microcrystalline silicon solar cells

表面背部反射层的应用；太阳能薄膜电池的光捕捉自组织/自有序化过程 形成的机理

Back surface reflectors(BSRs)with grating structures have been developed to enhance light trapping in thin-film hydrogenated microcrystalline Si(μc-Si:H)solar cells.As a grating structure, a periodic honeycomb-like dimple pattern with a period of

450 nm has been fabricated on Al substrates by a self-ordering process using anodic oxidation of Al.The clear diffraction effect has been confirmed on the patterned Al from the angle-dependent reflection.From quantum efficiency measurements, we found that the periodically patterned BSR can confine the incident light more effectively than the random textured BSR, especially at longer wavelengths.