Influence of Sodium and Rubidium Postdeposition Treatment on the Quasi-Fermi Level Splitting of Cu(In,Ga)Se2 Thin Films
Influence of Sodium and Rubidium Postdeposition Treatment on the Quasi-Fermi Level Splitting of Cu(In,Ga)Se2 Thin Films
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钠和铷沉积后处理对 Cu(In,Ga)Se2 薄膜准费米能级分裂的影响
DOI：
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发表时间：
2018
影响因子：
3
通讯作者：
S. Siebentritt
中科院分区：
文献类型：
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作者：
M. Wolter;B. Bissig;E. Avancini;R. Carron;S. Buecheler;P. Jackson;S. Siebentritt
研究了钠和铷后处理对Cu（In，Ga）Se_2薄膜吸收体质量的影响。准费米能级分裂（QFLS），通过光致发光（PL）测量，被用作吸收体的质量的度量。为了评估最先进的设备的分级吸收体中的QFLS值，有必要知道在哪个位置产生发光。在这里，我们表明，通过测量PL在不同的几何形状，光子起源于整体的带隙最小值内的散装。我们使用这些知识来比较不同吸收体中的QFLS，其中我们的结果表明，用NaF + RbF处理的吸收体中的QFLS高于仅用NaF处理或根本不处理的吸收体中的QFLS。我们将这种增加归因于减少非辐射复合，甚至在硫化镉沉积之前。相应的成品太阳能电池中QFLS和开路电压之间的差异减小也揭示了改进的CdS/CIGS界面。这两种效果最终导致更高的效率。
The influence of sodium and rubidium postdeposition treatment on the quality of Cu(In,Ga)Se2 thin-film absorbers is investigated. The quasi-Fermi level splitting (QFLS), measured via photoluminescence (PL), is used as the metric of quality of the absorber. To evaluate the QFLS values in the graded absorber of state-of-the-art devices, it is necessary to know at which location the luminescence is generated. Here we show, by measuring the PL in different geometries, that the photons originate from the global band gap minimum inside the bulk. We use this knowledge to compare the QFLS in different absorbers, where our results show that the QFLS is higher in absorbers that were treated with NaF + RbF than in absorbers that were only treated with NaF or not treated at all. We attribute this increase to a reduced nonradiative recombination, even before cadmium sulfide deposition. A decreased difference between QFLS and open-circuit voltage in the corresponding finished solar cells also reveals an improved CdS/CIGS interface. Both effects ultimately lead to a higher efficiency.