CuGa₃Se₅ is a promising candidate material with wide band gap for top cells in tandem photovoltaic and photoelectrochemical (PEC) devices. However, traditional CdS contact layers used with other chalcopyrite absorbers are not suitable for CuGa₃Se₅ due to the higher position of its conduction band (CB) minimum. Mg _x Zn_{1− x} O (MZO) is a transparent oxide with adjustable band gap and CB position as a function of magnesium composition, but its direct application is hindered by CuGa₃Se₅ surface oxidation. Here, MZO is investigated as a contact (n-type ‘buffer’ or ‘window’) material to CuGa₃Se₅ absorbers pretreated in Cd²⁺ solution, and an onset potential close to 1 V vs reversible hydrogen electrode in 10 mM hexaammineruthenium (III) chloride electrolyte is demonstrated. The Cd²⁺ surface treatment changes the chemical composition and electronic structure of the CuGa₃Se₅ surface, as demonstrated by photoelectron spectroscopy measurements. The performance of CuGa₃Se₅ absorber with Cd²⁺ treated surface in the solid-state test structure depends on the Zn/Mg ratio in the MZO layer. The measured open circuit voltage of 925 mV is promising for tandem PEC water splitting with CuGa₃Se₅/MZO top cells.

CuGa ₃ Se ₅是用于串联光伏和光电化学 (PEC) 器件中的顶部电池的有希望的宽带隙候选材料。然而，与其他黄铜矿吸收体一起使用的传统 CdS 接触层由于其导带 (CB) 最小值的较高位置而不适用于 CuGa ₃ Se _{5 。}Mg _x Zn _{1− x} O (MZO) 是一种透明氧化物，其带隙和CB 位置随镁成分的变化而变化，但其直接应用受到CuGa ₃ Se ₅表面氧化的阻碍。_{在这里，MZO 被研究为与 CuGa 3} Se的接触（n 型“缓冲”或“窗口”）材料 ^{展示了在 Cd 2+}溶液中预处理的_{5 个}吸收剂，并且在 10 mM 氯化六氨合钌 (III) 电解液中，与可逆氢电极相比，其起始电位接近 1 V。Cd ²⁺表面处理改变了CuGa ₃ Se ₅表面的化学成分和电子结构，如光电子能谱测量所示。在固态测试结构中具有Cd ²⁺处理表面的CuGa ₃ Se ₅吸收剂的性能取决于MZO层中的Zn/Mg比率。测得的 925 mV 开路电压有望用于与 CuGa ₃ Se _{5串联的 PEC 水分解}/MZO 顶部单元格。