图案化复合薄膜电极的制备及其调控薄膜太阳电池光电性能的机制研究

The introduction of patterned nanostructure and metal surface plasmon to the thin film solar cells can effectively enhance the absorption of incident light and results in increased efficiency. However, most proposed methods for constructing above mentioned patterned structures are time-consuming, high cost and limited to large-scale applications. In this proposal, patterned oxide-metal composites thin film will be fabricated as the back electrodes of amorphous silicon thin film solar cells through a combination of sol-gel and nanoimprint method. The composite films can enhance the light absorption of the solar cells by simultaneously using light trapping effects from the patterned nanostructure and scattering effect from the metal plasmon in a single layer. In this study, the modulation of the doping in the oxides and the content and distribution of the metal will be implemented to improve the conductivity of the composite film and reduce the parasitic absorption loss of the metal resulting in an improved collection of the light induced carriers. Our study will clarify the relationship between processing parameters and the optical and electrical properties of the composite film and also the mechanism of action of the processing. The influence rules of factors on the light trapping modes and carrier transportation will be revealed. These factors include the pattern feature sizes of the composite film, the content, shape, size and distribution of the metal and the doping dose of the oxides film. Our study will explore solution and provide theoretical guidance for the low-cost construction of novel patterned thin film electrode for the thin film solar cells.

在薄膜太阳电池中引入图案化纳米几何结构以及金属等离激元，可以有效增强电池对入射光的吸收，提高电池效率。但是，大多数构筑上述图案化结构的方法耗时，成本高，大规模应用受限。本项目拟采用将溶胶凝胶和纳米压印相结合的方法，制备一种新型的图案化氧化物-金属复合薄膜作为非晶硅薄膜太阳电池的背电极。该薄膜可以在一层薄膜中同时利用图案化纳米结构的多种陷光效应和金属等离激元的散射效应，增强电池的光吸收。本项目拟通过对氧化物的掺杂以及对金属含量、分布的调控，提高复合薄膜导电性，并降低金属等离子体损耗，促进光生载流子的收集。项目将阐明制备参数与复合薄膜光电特性之间的联系及其作用机制，揭示复合薄膜的图案特征尺寸，金属含量、形状、尺寸、分布，氧化物薄膜掺杂量等因素对薄膜太阳电池陷光模式和载流子输运的影响规律，为低成本构筑面向薄膜太阳电池的新型图案化薄膜电极探索解决方案和提供理论指导。

本项目开发了一种新颖的基于溶胶凝胶和纳米压印技术的制备图案化氧化锌-银复合薄膜透明电极的方法。采用该方法得到的复合薄膜电极电阻率可低达7.5×10-4 Ω·cm，在400-1000 nm波长范围内平均光透过率超过90%，并且在400°C的高温条件下处理后导电性能无衰减。该类型图案化ZnO/Ag复合薄膜电极为非晶硅薄膜太阳电池吸收层提供了更多的光吸收模式，显著提升了吸收层中的光场强度，并扩展了光场分布范围，从而增加了电池对光的利用程度，进而显著增加了电池的短路电流密度和光电转换效率。图案化结构的存在还使得薄膜太阳电池在弯曲过程中产生的应力得到有效的分散和缓解。这极大减少了电池失效的可能，可使电池经过十万次的弯折实验后性能几乎不发生衰减。.本项目提出的图案化复合薄膜电极制备方法简单，可实现大面积的卷对卷制造。该复合薄膜电极能够显著提升薄膜太阳电池的转换效率和耐弯折性能，在可穿戴式器件等领域具有较好的应用前景。本项目的研究成果也可为柔性光电器件的设计和制造提供一定参考价值。