Growth of Cu2ZnSnSe4 Film under Controllable Se Vapor Composition and Impact of Low Cu Content on Solar Cell Efficiency
Growth of Cu2ZnSnSe4 Film under Controllable Se Vapor Composition and Impact of Low Cu Content on Solar Cell Efficiency
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可控 Se 蒸气组成下 Cu2ZnSnSe4 薄膜的生长及低 Cu 含量对太阳能电池效率的影响
DOI：
10.1021/acsami.6b00081
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发表时间：
2016-04-27
影响因子：
9.5
通讯作者：
Zhang, Yi
中科院分区：
文献类型：
--
作者：
Li, Jianjun;Wang, Hongxia;Zhang, Yi
制备高质量低Cu含量（Cu/(Zn + Sn) < 0.8）的Cu2ZnSnSe4 （CZTSe）薄膜是一个挑战。本文采用直流溅射和后硒化方法研究了不同Se气相组成下CZTSe薄膜的生长机理。Se气相的组成对薄膜的致密性和膜中元素的扩散有重要影响。通过调整硒化过程中硒蒸气的组成，提出了一种优化的两步硒化工艺，得到了低Cu含量（Cu/(Zn + Sn) = 0.75）的高结晶CZTSe膜。进一步研究Cu含量对相应CZTSe太阳能电池形貌和光伏性能的影响，发现随着Cu含量的降低，CZTSe吸收膜的粗糙度增加。因此，CZTSe太阳能电池的反射损耗显著降低，电池的短路电流密度从Cu/(Zn + Sn) = 0.88时的34.7 mA/cm(2)提高到Cu/(Zn + Sn) = 0.75时的38.5 mA/cm(2)。此外，低Cu含量的CZTSe太阳能电池具有较长的少数载流子寿命和较高的开路电压。采用Cu/(Zn + Sn) = 0.75的CZTSe薄膜制备了效率为10.4%的冠军性能CZTSe太阳能电池。
It is a challenge to fabricate high quality Cu2ZnSnSe4 (CZTSe) film with low Cu content (Cu/(Zn + Sn) < 0.8). In this work, the growth mechanisms of CZTSe films under different Se vapor composition are investigated by DC-sputtering and a postselenization approach. The composition of Se vapor has important influence on the compactability of the films and the diffusion of elements in the CZTSe films. By adjusting the composition of Se vapor during the selenization process, an optimized two step selenization process is proposed and highly crystallized CZTSe film with low Cu content (Cu/(Zn + Sn) = 0.75) is obtained. Further study of the effect of Cu content on the morphology and photovoltaic performance of the corresponding CZTSe solar cells has shown that the roughness of the CZTSe absorber film increases when Cu content decreases. As a consequence, the reflection loss of CZTSe solar cells reduces dramatically and the short circuit current density of the cells improve from 34.7 mA/cm(2) for Cu/(Zn + Sn) = 0.88 to 38.5 mA/cm(2) for Cu/(Zn + Sn) = 0.75. In addition, the CZTSe solar cells with low Cu content show longer minority carrier lifetime and higher open circuit voltage than the high Cu content devices. A champion performance CZTSe solar cell-with 10.4% efficiency is fabricated with Cu/(Zn + Sn) = 0.75 in the CZTSe film without antireflection coating.