We study the impact of different alkali post‐deposition treatments by thermal admittance spectroscopy and temperature‐dependent current‐voltage (IVT) characteristics of high‐efficiency Cu(In,Ga)Se₂ thin‐film solar cells fabricated from low‐temperature and high‐temperature co‐evaporated absorbers. Capacitance steps observed by admittance spectroscopy for all samples agree with the widely observed N1 signature and show a clear correlation to a transport barrier evident from IVT characteristics measured in the dark, indicating that defects are likely not responsible for these capacitance steps. Activation energies extracted from capacitance spectra and IVT characteristics vary considerably between different samples but show no concise correlation to the alkali species used in the post‐deposition treatments. Numerical device simulations show that the transport barrier in our devices might be related to conduction band offsets in the absorber/buffer/window stack.

中文翻译：

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Cu（In，Ga）Se2薄膜吸收剂的碱处理及其对运输壁垒的影响

我们通过热导率光谱法研究了不同碱后处理的影响，以及由低温和高温制备的高效Cu（In，Ga）Se ₂薄膜太阳能电池的温度相关电流-电压（IVT）特性温度共蒸发吸收器。通过导纳光谱法观察到的所有样品的电容阶跃与广泛观察到的N1特征一致，并且与在黑暗中测得的IVT特性所显示的传输势垒之间具有明显的相关性，表明缺陷可能与这些电容阶跃无关。从电容谱和IVT提取的活化能不同样品之间的特性差异很大，但与沉积后处理中使用的碱类物质没有明确的相关性。数值设备仿真表明，我们设备中的传输障碍可能与吸收器/缓冲器/窗口堆栈中的导带偏移有关。