Park Cheolmin, Balaji Nagarajan, Jung Sungwook, Choi Jaewoo, Ju Minkyu, Lee Seunghwan, Kim Jungmo, Bong Sungjae, Chung Sungyoun, Lee Youn-Jung, Yi Junsin
J Nanosci Nanotechnol. 2015 Oct;15(10):7699-705. doi: 10.1166/jnn.2015.11206.
High-efficiency Si solar cells have attracted great attention from researchers, scientists, photovoltaic (PV) industry engineers for the past few decades. With thin wafers, surface passivation becomes necessary to increase the solar cells efficiency by overcoming several induced effects due to associated crystal defects and impurities of c-Si. This paper discusses suitable passivation schemes and optimization techniques to achieve high efficiency at low cost. SiNx film was optimized with higher transmittance and reduced recombination for using as an effective antireflection and passivation layer to attain higher solar cell efficiencies. The higher band gap increased the transmittance with reduced defect states that persisted at 1.68 and 1.80 eV in SiNx films. The thermal stability of SiN (Si-rich)/SiN (N-rich) stacks was also studied. Si-rich SiN with a refractive index of 2.7 was used as a passivation layer and N-rich SiN with a refractive index of 2.1 was used for thermal stability. An implied Voc of 720 mV with a stable lifetime of 1.5 ms was obtained for the stack layer after firing. Si-N and Si-H bonding concentration was analyzed by FTIR for the correlation of thermally stable passivation mechanism. The passivation property of spin coated Al2O3 films was also investigated. An effective surface recombination velocity of 55 cm/s with a high density of negative fixed charges (Qf) on the order of 9 x 10(11) cm(-2) was detected in Al2O3 films.
在过去几十年里，高效硅太阳能电池一直备受研究人员、科学家以及光伏产业工程师的关注。对于薄硅片而言，表面钝化变得十分必要，以便通过克服因晶体硅相关晶体缺陷和杂质所引发的多种诱导效应来提高太阳能电池的效率。本文探讨了合适的钝化方案及优化技术，以低成本实现高效率。对氮化硅薄膜进行了优化，使其具有更高的透过率并减少复合，用作有效的减反射和钝化层以获得更高的太阳能电池效率。更高的带隙增加了透过率，同时减少了氮化硅薄膜中在1.68和1.80电子伏特时仍然存在的缺陷态。还研究了富硅氮化硅/富氮氮化硅叠层的热稳定性。折射率为2.7的富硅氮化硅用作钝化层，折射率为2.1的富氮氮化硅用于热稳定性。烧制后的叠层获得了720毫伏的隐含开路电压以及1.5毫秒的稳定寿命。通过傅里叶变换红外光谱分析了硅 - 氮和硅 - 氢键合浓度，以研究热稳定钝化机制的相关性。还研究了旋涂氧化铝薄膜的钝化性能。在氧化铝薄膜中检测到有效表面复合速度为55厘米/秒，以及约9×10¹¹厘米⁻²数量级的高密度负固定电荷（Qf）。
