Condensed Matter Physics of Energy Materials, Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden.
Division of Applied Physical Chemistry, Department of Chemistry, KTH - Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
ACS Appl Mater Interfaces. 2023 Mar 8;15(9):12485-12494. doi: 10.1021/acsami.2c17527. Epub 2023 Feb 27.
A heterojunction is the key junction for charge extraction in many thin film solar cell technologies. However, the structure and band alignment of the heterojunction in the operating device are often difficult to predict from calculations and, due to the complexity and narrow thickness of the interface, are difficult to measure directly. In this study, we demonstrate a technique for direct measurement of the band alignment and interfacial electric field variations of a fully functional lead halide perovskite solar cell structure under operating conditions using hard X-ray photoelectron spectroscopy (HAXPES). We describe the design considerations required in both the solar cell devices and the measurement setup and show results for the perovskite, hole transport, and gold layers at the back contact of the solar cell. For the investigated design, the HAXPES measurements suggest that 70% of the photovoltage was generated at this back contact, distributed rather equally between the hole transport material/gold interface and the perovskite/hole transport material interface. In addition, we were also able to reconstruct the band alignment at the back contact at equilibrium in the dark and at open circuit under illumination.
异质结是许多薄膜太阳能电池技术中电荷提取的关键结。然而，工作器件中异质结的结构和能带排列通常难以通过计算来预测，并且由于界面的复杂性和狭窄厚度，难以直接测量。在这项研究中，我们展示了一种使用硬 X 射线光电子能谱 (HAXPES) 在工作条件下直接测量全功能卤化铅钙钛矿太阳能电池结构的能带排列和界面电场变化的技术。我们描述了太阳能电池器件和测量设置中所需的设计考虑因素，并展示了太阳能电池背面的钙钛矿、空穴传输和金层的结果。对于所研究的设计，HAXPES 测量表明 70%的光电压在此背接触处产生，在空穴传输材料/金界面和钙钛矿/空穴传输材料界面之间相当均匀地分布。此外，我们还能够在黑暗中和在光照下开路时重建背接触处的平衡能带排列。
