In this work, we used K‐rich glass substrates to provide potassium during the coevaporation of Cu(In,Ga)Se₂ (CIGS) absorber layers. Subsequently, we applied a postdeposition treatment (PDT) using KF or RbF to some of the grown absorbers. It was found that the presence of K during the growth of the CIGS layer led to cell efficiencies beyond 17%, and the addition of a PDT pushed it beyond 18%. The major finding of this work is the observation of discontinuous 100‐ to 200‐nm‐deep Cu‐depleted patches in the vicinity of the CdS buffer layer, correlated with the presence of K during the growth of the absorber layer. The PDT had no influence on the formation of these patches. A second finding concerns the composition of the Cu‐depleted areas, where an anticorrelation between Cu and both In and K was measured using scanning transmission electron microscopy. Furthermore, a steeper Ga/(In+Ga) ratio gradient was measured for the absorbers grown with the presence of K, suggesting that K hinders the group III element interdiffusion. Finally, no Cd in‐diffusion to the CIGS layer could be detected. This indicates that if Cd_Cu substitution occurs, either their concentration is below our instrumental detection limit or its presence is contained within the first 6 nm from the CdS/CIGS interface.

中文翻译：

---

高效Cu（In，Ga）Se2太阳能电池吸收器中K诱导的深表面Cu耗竭

在这项工作中，我们使用富含K的玻璃基底在Cu（In，Ga）Se ₂的共蒸发过程中提供钾。（CIGS）吸收层。随后，我们对一些生长的吸收剂进行了使用KF或RbF的沉积后处理（PDT）。发现在CIGS层生长期间钾的存在导致电池效率超过17％，而PDT的添加使钾效率超过18％。这项工作的主要发现是在CdS缓冲层附近观察到不连续的100至200 nm深的贫铜斑块，这与吸收层生长过程中K的存在有关。PDT对这些补丁的形成没有影响。第二个发现涉及贫铜区域的组成，其中使用扫描透射电子显微镜测量了铜与In和K的反相关性。此外，对于在存在K的情况下生长的吸收剂，测得的Ga /（In + Ga）比梯度更陡，表明K阻碍了III类元素的相互扩散。最终，没有检测到Cd扩散到CIGS层中。这表明如果镉发生_铜取代，或者它们的浓度低于我们的仪器检测极限，或者它的存在存在于CdS / CIGS界面的前6 nm之内。