Realizing photovoltaic devices that achieve the full potential of the metal halide perovskite material will require improved insight regarding the role of selective contacts and how key interfaces operate when mobile defects are present. However, measuring interface properties in typical device stacks where the perovskite layer is thin and sandwiched between two contacts has been a challenge. Here, we fabricate p-i-n and p-n lateral heterojunctions with nickel oxide/titanium oxide all back contacts, permitting us to employ a comprehensive analysis approach, including ultraviolet and X-ray photoemission spectroscopy (UPS/XPS), angle-resolved X-ray absorption spectroscopy (XAS), Kelvin probe force microscopy (KPFM), surface photovoltage (SPV), hyperspectral imaging (HSI), and time-resolved fluorescence lifetime imaging microscopy (TR-FLIM) to discern the role of selective contacts. Specifically, we tune the selectivity of the contacts, changing the gradient in the carrier concentration across the surface of the active layer, which is connected to carrier extraction at the buried interface, and thus the device functionality.

实现能够发挥金属卤化物钙钛矿材料全部潜力的光伏器件将需要更深入地了解选择性接触的作用以及存在移动缺陷时关键界面的运作方式。然而，在钙钛矿层很薄且夹在两个触点之间的典型器件堆栈中测量界面特性一直是一个挑战。在这里，我们制造了带有氧化镍/氧化钛所有背接触的 pin 和 pn 横向异质结，使我们能够采用综合分析方法，包括紫外线和 X 射线光电发射光谱 (UPS/XPS)、角分辨 X 射线吸收光谱(XAS)、开尔文探针力显微镜 (KPFM)、表面光电压 (SPV)、高光谱成像 (HSI)、和时间分辨荧光寿命成像显微镜 (TR-FLIM) 来辨别选择性接触的作用。具体来说，我们调整触点的选择性，改变有源层表面的载流子浓度梯度，这与掩埋界面处的载流子提取有关，从而影响器件功能。