Recently, the research group led by Dr. Hou Fuhua from the School of Physical Science and Technology at our university studied the enhanced carrier transport effect of molybdenum oxide at the interface between the hole transport layer and the back electrode in wide bandgap perovskite solar cell structures, revealing the fixed negative charge passivation effect of molybdenum oxide at this interface. The related results were published in the academic journal "Applied Physical Letters" (Nature Index included) under the title "Highly efficient wide-bandgap perovskite solar cells prepared by fixing charge passivation in the interface layer".
In wide bandgap perovskite solar cells, severe stress on the surface of the perovskite film extends to the interface between the carrier transport layer and the metal electrode, resulting in an increase in surface roughness of the carrier transport layer. The adverse effects of such roughness will weaken the carrier transport efficiency at the interface, thereby affecting the overall stability of the device. To solve this problem, a method that can effectively optimize the carrier transport path is needed to improve the performance and stability of the device.
This study proposes a design scheme for a local contact structure to address the interface issues of wide bandgap perovskite solar cells. By vacuum depositing a specific thickness of molybdenum oxide intermediate layer on the interface between the hole transport layer and the metal electrode, the carrier transport path is changed to improve the stability and efficiency of the device. The local contact structure of molybdenum oxide was characterized using Kelvin probe force microscopy, capacitance voltage characteristics, electrochemical impedance spectroscopy, and X-ray photoelectron spectroscopy. Research has found that the molybdenum oxide intermediate layer generates negative fixed charges at the hole transport layer/metal interface, changes the carrier concentration distribution, enhances the built-in voltage, and promotes carrier transport near the interface. Compared with wide bandgap perovskite solar cells without local contact structure of molybdenum oxide, the optimized device has significantly improved overall performance, especially in terms of thermal stability and photostability.
This study was supported by the National Natural Science Foundation of China, the Key Science and Technology Project of Higher Education Institutions in Inner Mongolia Autonomous Region, the Research Support Project for Introducing High level Talents at the Inner Mongolia Autonomous Region Level, and the High-level Talent Introduction Project of the Junma Plan of Inner Mongolia University. In this work, Researcher Hou Fuhua is the sole corresponding author, and our research group's 2021 master's student Guo Haikuo and 2022 master's student Guo Jingwei are co-first authors. Inner Mongolia University is the sole completion unit.
Paper link: https://doi.org/10.1063/5.0217393
