基于能带补偿的纳米硅/晶硅异质结电池的界面修饰与调控

Nanocrystalline silicon (nc-Si)/crystalline silicon(c-Si) heterojunction solar cells is one of the preferred structures of high efficiency and low-cost. Compared to amorphous silicon (a-Si)/c-Si heterojunction, nc-Si/c-Si heterojunction posses better electrical properties. However, many kinds of defects around the interface results in the increase of photo-generated carrier recombination rate and the reduction of conversion efficiency. Therefore, it is urgent for in-depth analysis of the heterojunction interface states and carrier transport rules. Exploring the technology about modification and regulation of the heterojunction interface defects to passivate the interface defect states is very important. The project introduced innovatively nc-Si with adjustable band gap to decorate the interface of nc-Si/c-Si heterojunction and to solve the matter of band mismatch. We investigate the effect of the work function of transparent electrode on the transportation of carrier in the surface of the emitter layer. Effective contact between the transparent electrode and the emission layer can be obtained by regulation of the work function of the transparent electrode, so as to increase collection efficiency of photo-generated carrier. Mechanisms of effectively separation, transport and collection of photo-generated carrier around the interface will be illustrated. The origin of carrier recombination interface and the access of regulation mechanism of carrier transport will be explored to further improve efficiency of nc-Si/c-Si heterojunction devices. These will lay a good foundation for the analysis and regulation of the interfaces of other semiconductor heterojunction devices.

纳米硅/晶硅异质结电池是新型高效低成本电池的首选结构之一，其相对于非晶/晶硅异质结具有更优良的电学特性，该异质结的界面缺陷是导致光生少子的复合几率增加，器件转化效率降低的关键因素。因此，迫切需要深入研究异质结界面状态、缺陷起源与分布及载流子输运规律，探索异质结界面缺陷修饰和调控技术来钝化界面缺陷态。本项目创新性地通过纳米硅薄膜的带隙调控实现对纳米硅/晶硅异质结进行界面缺陷修饰与能带失配调控；研究透明电极功函数对发射层表面的载流子传输性能的影响，对透明电极功函数进行调控，实现透明电极与发射层的有效接触，增加光生载流子收集效率。利用界面修饰技术实现高效纳米硅/晶硅异质结太阳电池的制备。研究界面光生载流子的分离、传输和收集机理。探索界面载流子复合的起源，获得载流子输运的调控机制，进一步提高纳米硅/晶硅异质器件效率。对其他半导体异质结器件界面的分析与调控也具有借鉴意义。

纳米硅/晶硅异质结电池是新型高效低成本电池的首选结构之一，异质结的界面缺陷是导致光生少子的复合几率增加，器件转化效率降低的关键因素。探索异质结界面缺陷修饰和调控技术来钝化界面缺陷态是急需要解决的关键问题。本项目通过纳米硅薄膜的带隙调控实现对纳米硅/晶硅异质结进行界面缺陷修饰与能带失配调控；研究透明电极功函数对发射层表面的载流子传输性能的影响，对透明电极功函数进行调控，实现透明电极与发射层的有效接触，增加光生载流子收集效率。利用界面修饰技术实现高效纳米硅/晶硅异质结太阳电池的制备。研究界面光生载流子的分离、传输和收集机理。探索界面载流子复合的起源，获得载流子输运的调控机制，进一步提高纳米硅/晶硅异质器件效率。优化了a-Si,nc-Si,a-SiC,a-SiN,薄膜的制备技术，获得优化的PECVD制备工艺参数，对工艺过程中薄膜形成与量子点演化机理以及与电池界面的能带补偿等方面开展了深入研究，对ZnO的B、Al掺杂、掺杂机理以及作为TCO薄膜用于HIT电池中的作用、与电池的能带结构匹配、界面特性以及BSF效果等方面从理论和工艺技术角度开展了深入研究，分析了本征层、纳米硅薄膜、MoS2/c-Si界面态以及能带补偿对TCO/n-type MoS2/i-layer nc-Si:H/p-type c-Si/Al HIT太阳能电池性能的影响规律。采用优化的结构和工艺技术制备了异质结电池，电池转换效率19.1%，填充因子79.69%，短路电流8.133A，输出开路电压704mV。发表期刊论文15篇，会议论文5篇，会议报告5篇，授权中国发明专利6项，实用新型1项，正在申请发明专利5项。培养本科生27人，硕士生6人，博士生3人。这些工作对其他半导体异质结器件界面的分析与调控也具有借鉴意义。