高效背接触硅异质结太阳电池基础研究

Structure parameters of silicon heterojunction back contacted (HBC) solar cells will be optimized by simulation via numerical software. By combining with some experiments including temperature and illumination intensity dependent I-V curve testing, the carrier transport mechanism will also be made clear. In order to increase the short-circuit current density of the solar cell, "black silicon" will be prepared on silicon substrate to lower the surface reflection by a novel wet-chemical etching method we proposed here based on the silicon oxidation induced by high valence metallic salt. The corresponding chemical reaction mechanism will be investigated carefully. In order to enhance the open-circuit voltage of the solar cell, high performance passivation layers will be conformally deposited on the above "black silicon" surface via atomic layer deposition (ALD) by anaylizing the growth mechanism of the passivation layers and the relationship between the material microstructure and the passivation properties. Further, silicon based materials, including the passivation layer, the emitter layer and the back surface field (BSF) layer, in heterojunction regions will be prepared by hot wire chemical vapor deposition (HWCVD). By controlling the oxygen content in some layers, the anti-etching property can be modified. And thus the wet chemical etching can stop at the heterojunction interface between two different materials by itself. So the periodic back contacted regions of the emitter and the BSF can be fabricated by screen printing process with high open-circuit voltage and fill factor. Based on the above results, the conversion efficiency of HBC solar cell can be increased to above 24%.

采用数值模拟软件模拟给出背接触硅异质结（HBC）太阳电池的优化结构参数，并结合变温变光强I-V 曲线测试等实验手段，揭示电池的载流子输运机制。通过创新采用可变价金属的高价金属盐做氧化剂对硅衬底进行湿法化学腐蚀制备“黑硅”结构，研究分析其化学反应机理，制备出表面清洁并易于钝化的"黑硅"表面，提高电池的短路电流。通过研究原子层沉积（ALD）制备钝化介质层的生长机制，揭示介质层内部微结构与钝化性能之间的关系，实现"黑硅"表面的优异钝化，提高电池的开路电压。进一步研究热丝化学气相沉积（HWCVD）制备用于结区钝化层、发射极层和背场层的硅基材料的生长规律，通过材料组分调节控制材料层在酸/碱腐蚀液中的被腐蚀能力，实现腐蚀在两种不同材料界面处的自终止，由此基于丝网印刷制备出优异的发射极区和背场区交替分布的背接触结构，提高电池开路电压的同时改善电池填充因子。最终使电池效率大于24%。

全背接触晶硅异质结（HBC）太阳电池是将叉指状全背接触（IBC）电池的高短路电流和晶硅异质结（SHJ）电池的高开路电压相结合的高效晶硅太阳电池，创造了目前26.7%的国际最高效率，被认为是晶硅太阳电池的重要发展方向，但至今未形成可行的低成本技术路线。.本项目采用模拟软件AFORS-HET、Quokka研究了太阳电池结构参数变化对电池性能的影响，揭示了电池的载流子输运机制，给出了HBC太阳电池的优化结构设计。开发了利用含可变价锰离子的固体二氧化锰颗粒作氧化剂对硅衬底进行氧化腐蚀制备“黑硅”结构的新方法以及基于碱溶液电化学腐蚀制备多孔硅减反射结构的新方法，研究分析了其化学反应机理，有效降低了硅衬底的表面反射率。通过原子层沉积（ALD）制备了AlOx钝化层，揭示了介质层内部微结构与钝化性能间的关系，并研究揭示了AlOx/SiNx复合层的钝化规律。通过等离子体化学气相沉积（PECVD）和热丝化学气相沉积（HWCVD）制备硅基薄膜材料，开发了高性能a-Si:H钝化层和nc-SiOx:H掺杂层。基于激光刻划结合湿化学腐蚀实现了电池局域背接触区的图形化，通过工艺集成制备了HBC太阳电池。.本项目验证了HBC太阳电池低成本制备的可行性，为先进HBC电池的成熟制备奠定了研究基础，通过进一步的工艺优化，能够进一步提升HBC太阳电池的性能，并形成真正实用的制备路线，为我国光伏产业技术升级做出重要贡献。