喷墨打印太阳能电池片栅线电极三维形貌工艺优化研究

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题名	喷墨打印太阳能电池片栅线电极三维形貌工艺优化研究
作者	张磊
学位类别	博士
答辩日期	2015-11-22
授予单位	中国科学院沈阳自动化研究所
授予地点	中国科学院沈阳自动化研究所
导师	朱云龙
关键词	喷墨打印流体体积法咖啡环太阳能电池栅极银导线高宽比
其他题名	Research on Inkjet Printed Front Side Fine Line Morphology Optimization on Crystalline Silicon Solar Cells
学位专业	机械电子工程
中文摘要	本论文采用喷墨打印技术将纳米银墨水直接打印到硅基太阳能电池上，在线加热使之固化实现太阳能电池栅极一次成型。通过控制打印分辨率、打印层数、在线固化温度等参量，消除“咖啡环”和“马鞍型”等表面形貌缺陷，实现高“高宽比”栅极制造。研究的内容包括：微液滴喷射数值建模、液滴撞击固体平壁面数值建模、太阳能电池超细栅电极样机系统研发、实验验证及栅极喷印工艺优化研究。具体的研究内容和创新性成果概括如下：(1) 采用压力波传递模型作为喷嘴口的压力入口边界，解决了工业喷墨头压电陶瓷体参数无法获取的难题，简化了压电喷射数值模型。基于流体体积法对微液滴喷射过程进行数值建模与仿真，研究压力波幅值、脉冲宽度及墨水粘度、表面张力对低粘度纳米银墨水稳定喷射行为的影响。并通过实验验证了该模型的有效性。该模型有助于深入理解微液滴喷射机理，通过优化压力波幅值及脉冲宽度等参数，实现速度、尺度均匀的微液滴流，为后续工艺实验奠定良好基础；同时，通过优化墨水粘度和表面张力等物性参数，使液滴流进入喷射稳定区间，为纳米银墨水研发提供数据支撑。(2) 太阳能电池多晶硅基材经过表面制绒后具有独特的表面特性，微液滴撞击多晶硅基材后的形变过程对金属化栅极的均匀性和一致性具有重要影响。实验观测方法需要精密、复杂的专用仪器，且只能观测到液滴撞击过程的形貌变化，对于撞击过程中液滴内部的流场状态无法直接观测，而真正决定液滴形态的重要因素是其内部流场。针对上述问题，本文基于有限体积法对液滴撞击固体平壁面进行数值建模，仿真求解过程采用PISO算子对液滴变形过程的流场压力进行修正，从而对液滴撞击壁面的动态过程及其内部压力和速度分布进行深入研究，并重点分析了壁面浸润性、撞击速度对液滴撞击固体壁面后动态特性的影响。解决了液滴撞击过程中液滴内部流流场状态无法直接观测的问题，为栅极打印优化实验提供重要的理论支撑。(3) 太阳能电池超细栅电极喷印系统包含多组耦合模块且具有强实时性，采用单一状态机进行系统级设计复杂度较高且难以维护。针对此问题，在系统设计方面提出主从并行状态机建模方法设计方法，实现不同时钟域的从状态机并行控制，系统采用6组抽屉式冗余喷头阵列设计，每组阵列8组喷墨头，实现90条超细栅电极一次性喷印制造。通过优化分辨率参量实现对打印栅极宽度的可控，并进行了实验验证，为栅极打印工艺优化实验的开展奠定了良好的基础。(4) 以纳米银墨水作为喷墨材料，以多晶硅硅片为打印基材，在样机系统进行工艺优化实验。通过优化在线固化温度，消除“咖啡环”和“马鞍型”缺陷对栅极三维形貌的影响；通过优化喷印分辨率获取栅极最窄宽度；通过优化喷印层数得到高“高宽比”的栅极。喷墨打印制备太阳能电池栅极工艺与传统的丝网印刷工艺相比较，形成的栅极宽度≦40μm，高宽比≧0.6，且三维形貌光滑均匀，由于采用非接触印刷工艺，硅片破碎率<0.1%，烧结温度在200℃时，电阻率低至5.04×10-6Ohm.cm。
英文摘要	In this paper, the nano silver ink is directly printed onto the silicon based solar cell by the ink jet printing technology, and the online heating can be used to realize the fine line metallation of the solar cell. By controlling the parameters such as the print resolution, the number of layers, and the on-line curing temperature, the surface morphology of the coffee ring is eliminated. The contents of the paper include: the micro droplet spray numerical modeling, the solar cell fine line matellization prototype system development, the experimental verification and the fine line ink-jet printing technology research. Specific research contents and innovative results are summarized as follows: (1) The pressure inlet boundary is induced based on the theory of wave propagation to simplify the droplet ejection model and to solve the problem that the parameters of piezoelectric ceramics are difficult to be obtained. The numerical model and simulation of micro droplet ejection is established based on volume of fluid. The influence of the pressure amplitude, pulse width and ink viscosity and surface tension on the low viscosity nano silver ink is also discussed. And the validity of the model is verified by experiments. The model is helpful to understand the mechanism of micro droplet injection, and can realize the speed and size uniformity of micro droplet flow by optimizing the parameters such as pressure amplitude and pulse width. Meanwhile, the viscosity and surface tension of ink are optimized for nano-silver ink research. (2) The etched polycrystalline silicon solar cell has unique feather. The deformation that droplet impacts on the substrate plays a great role for fine line metallization. Meanwhile, it is difficult to experimental observations for micro droplet impinging on the horizontal wall surface. Therefore, the numerical modeling and simulation of liquid droplets impinging on a rigid substrate are established based on finite volume method. PISO solver is induced to revise the fluid pressure field. The morphology, internal pressure and the velocity vector variation are in-depth understanding. Numerical modeling and Simulation of the double drop impact horizontal wall is carried out to investigate the mechanism of the double drop collision, and reveal the effect of dynamic pressure on the droplet flow. (3) The prototype of the solar cell fine line matellization contains some coupling and strong real time functional modules. It is difficult to design by single state machine. Therefore, The master-slave machine is induced to design the prototype system. The prototype is designed and realized by using the multi-group piezo print head arrays. The prototype system can manufacture multi-fine-lines matellization by multi-pass printing. It greatly improves the efficiency of the fine lines manufacturing. The printing resolution is optimized to control the width of fine line and verified by experiment. (4) Experimental study on the morphology of fine line matellization is carried out from the aspects of the printing resolution, the number of the layers and the temperature of substrate. The width of printed fine line is less than 40μm, aspect ratio is higher than 0.6. And three-dimensional morphology is smooth. Due to the non-contact printing process, wafer broken ratio is less than 0.1%. Fine line resistivity is as low as 5.04 * 10-6Ohm.cm when sintering temperature is 200℃.
语种	中文
产权排序	1
公开日期	2015-12-27
页码	116页
内容类型	学位论文
源URL	[http://ir.sia.ac.cn/handle/173321/17527]
专题	沈阳自动化研究所_信息服务与智能控制技术研究室
推荐引用方式 GB/T 7714	张磊. 喷墨打印太阳能电池片栅线电极三维形貌工艺优化研究[D]. 中国科学院沈阳自动化研究所. 中国科学院沈阳自动化研究所. 2015.