The persistent photoconductivity (PPC), i.e., the metastable increase in hole concentration due to light soaking in Cu-poor Cu(In_0.7,Ga_0.3)Se₂ solar cells is observed to be proportional to the Na concentration in the absorber layer. Hole concentration in cells and conductivity in thin films follow a similar trend, suggesting that the effect originates from the absorber layer and is somehow linked to sodium concentration. Our results suggest that the large lattice relaxation model of an amphoteric V_Se–V_Cu vacancy complex being responsible for PPC cannot itself explain the Na-PPC relation. Therefore. either the passivation of the grain boundary barriers by sodium or a sodium-related modification of a defect complex needs to be included in the model.

中文翻译：

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Cu(In,Ga)Se$_{2}$太阳能电池和薄膜中钠含量对持久光电导率的依赖性

观察到持续光电导率 (PPC)，即由于光浸入贫铜 Cu(In _0.7 ,Ga _0.3 )Se ₂太阳能电池而导致空穴浓度的亚稳态增加，与吸收层中的 Na 浓度成正比。电池中的空穴浓度和薄膜中的电导率遵循类似的趋势，这表明该效应源于吸收层，并以某种方式与钠浓度有关。我们的结果表明，两性晶体的大晶格弛豫模型伏_硒-伏负责 PPC 的_Cu空位复合物本身不能解释 Na-PPC 关系。所以。模型中需要包括钠对晶界势垒的钝化或缺陷复合物的钠相关修饰。