Low‐temperature atomic layer deposited (ALD) TiO₂ is an electron transport layer that is relatively unreactive with mixed halide perovskite semiconductors. This amorphous, ALD‐grown metal oxide is typically interposed between the perovskite layer and a low work function metal electrode, prompting interest in the electronic and chemical structure of the resulting TiO₂/metal interface. Here, the interfaces between TiO₂ and two common metal low work function electrodes, polycrystalline thin films of silver and aluminum are studied. It is found that a Schottky barrier forms between Ag and low‐temperature ALD‐grown TiO₂, consistent with the observed solar cell current–voltage characteristics, and confirmed by in situ measurement of Ag deposition‐induced core level shifts in X‐ray photoelectron spectra and barrier height extraction from temperature‐dependent current–voltage data. On the other hand, Al reacts chemically with the surface of TiO₂ during its deposition. The resulting interface acts as an Ohmic contact, due to the apparent oxygen vacancy doping of the underlying ALD‐TiO₂. These findings provide lessons for metal electrode selection in future halide perovskite device structures.

中文翻译：

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低温原子层沉积的TiO2电子传输层与金属电极的连接

低温原子层沉积（ALD）TiO ₂是电子传输层，与混合卤化物钙钛矿半导体相对不反应。这种无定形的，ALD生长的金属氧化物通常介于钙钛矿层和低功函金属电极之间，引起人们对所得TiO ₂ /金属界面的电子和化学结构的兴趣。在这里，研究了TiO ₂与两个常见的金属低功函数电极，银和铝的多晶薄膜之间的界面。发现在Ag和低温ALD生长的TiO ₂之间形成了肖特基势垒，与观察到的太阳能电池电流-电压特性相一致，并通过X射线光电子能谱中Ag沉积引起的核心能级位移的原位测量以及从与温度相关的电流-电压数据中提取势垒高度来证实。另一方面，Al在沉积期间与TiO ₂的表面化学反应。由于下面的ALD-TiO ₂明显的氧空位掺杂，最终的界面充当了欧姆接触。这些发现为未来卤化物钙钛矿器件结构中金属电极的选择提供了经验教训。