基于网格银的高效柔性大面积太阳能电池的制备和性能研究

Recent breakthroughs in organic solar cells (OSCs) have led to devices with power conversion efficiency (PCE) over 10%. These high efficiency results are obtained on glass/ITO electrodes with cell area typically no more than 0.1 cm2. The PCE of large-area OSCs (> 1cm2) are significantly lagging behind. In previous work, we obtained large-area high-efficiency OSCs using Ag-grid based hybrid electrodes with 84% transparency and ultra-low sheet resistance of 1.2 Ω sq-1. Inverted OSCs with device area of 1.21 cm2 exhibited a PCE of 5.85%, which is the highest in large-area flexible OSCs (>1 cm2) up to date. Here we propose to further improve the PCE of large-scale flexible OSC by means of developing flexible electrodes with high transparency and ultra-low sheet resistance and introducing new high-performance the active materials. First, branching pattern will be introduced to the silver grid substrate to improve the collection of the carriers while keep the high transparency and low surface resistance. Vapor-phase polymerized PEDOT (VPP-PEDOT) will be employed to reduce the surface resistance of the composite electrode and obtain a smooth surface. Organic perovskite materials will be applied as the active layer to improve the photoelectric conversion efficiency (PCE). Through adjusting the composition of the precursor solution and the drying method, the effect of the morphology of the active layer on the PCE of the devices will be investigated. VPP-PEDOT will be modified by ionic doping to get an appropriate work function as the hole collection layer. Furthermore, the application of VPP-PEDOT will avoid the introduction of polystyrene sulfonic acid (PSS) and thus avoid device deterioration mechanisms associated with PSS. Finally, this project also intends to develop a new type of large-area coating technique such as pressure coating, which could obtain a film with high flatness and high quality by controlling parameters of the coating techniques. Through this coating method, flexible solar cells with more than 10 cm2 area and good PCE will be prepared.

目前小面积（～0.1cm2）有机太阳能电池单节效率已接近10%，但是大面积（>1 cm2）器件的效率却大大落后，因此制备大面积高效率的单节电池对于提高电池模组的性能和有机太阳能电池的实际应用前景至关重要。我们在前期工作中研发了基于网格银导电膜的杂化柔性电极（84%透过率，1.2 Ω sq-1），并得到了效率为5.85 %的大面积（1.21 cm2）太阳能电池器件，是目前基于有机活性层面积1cm2以上器件的最高效率。本项目提出通过继续改进电极性能和利用新的高效活性材料来进一步提高大面积器件的效率。本项目拟在优化高分辨率网格银杂化电极基础上引入高效的有机钙钛矿材料，结合气相聚合PEDOT高导电、功函可调及可控生长的优势，提高器件的效率和寿命，并发展大面积涂膜方法制备高性能柔性大面积太阳能电池，探索制约大面积太阳能电池性能的因素，推动柔性太阳能电池的实际应用。

目前有机和钙钛矿单节太阳能电池的认证效率已分别突破15%和23%，极具应用前景。但目前的高效率器件多为小面积电池（～0.1 cm2），而大面积电池（>1 cm2）的器件效率大大落后。在实际应用中，太阳能电池模块包含电池活性区和由导线，汇流条，分隔区等组成的非活性区，增大电池面积可以提高电池区域在模组中的占比，因此亟需推动大面积高效率有机和钙钛矿电池的研究以提高电池模组性能。目前制约大面积器件研究的核心技术难题包括：1.常规透明导电电极如ITO、FTO等较大的方块电阻导致较大的能量损失，2. 制备小面积器件常用的旋涂工艺难以胜任大面积电池制备需求。本项目中，我们以前期工作中报道的网格银透明导电基底为基础，一方面继续改进电极参数和提高器件性能，另一方面发展大面积涂膜工艺，为高效率大面积器件的发展奠定基础。研究结果表明，通过优化网格银图案和杂化电极的匹配程度，可以在降低方块电阻的同时不牺牲透光率，我们基于此电极制备的1.21 cm2的电池效率达14.72%。同时，我们搭建微凹版涂膜设备探索大面积涂膜工艺，成功制得16 cm2的大面积电池。我们进一步地结合扫描探针显微镜证实，有机和钙钛矿电池活性层光电性质及其界面势垒是大面积器件性能的关键制约因素之一。

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