Recently, the team of Academician Lu Zhenghong of School of Physics and Astronomy of Yunnan University, and the team of Peking University, Researcher Zhu Rui, and the team of Academician Gong Qihuang of Academician in the international authoritative journal Energy & Environmental Science (IF=39.7) published research results entitled "Halogen Cracked by in the organic anchored perovskite surface " (DOI: 10.1039/d2ee02698h). This work reveals the key interface structure of stable perovskite solar cells . Doctoral student Hu Juntao of Yunnan University and Doctoral student Chen Peng of Peking University are co-first authors of the paper. Academician Lu Zhenghong, researcher Zhu Rui of Peking University, and postdoctoral student of the University of Toronto are co-corresponding authors of the paper. The authors of this work also include members of the team of Professor Samuel D. Stranks of the Cavendish Laboratory of Cambridge University.
perovskite forms barrier-free contact with the charge transport layer. It is the key to achieving stable and efficient perovskite solar cells. After the perovskite surface is passivated by large volume cation , the efficiency of the prepared solar cells has repeatedly set new world records. Although these large volumes of cations (such as phenethylamine salt cations, PEA+) are believed to form 2D or quasi-2D perovskites in the light absorption layer, it is not clear how these complex surface chemical reactions occur. In situ photoelectron energy spectroscopy can simultaneously detect the chemical and electronic structures of perovskite surfaces and interfaces, thus helping researchers to gain an in-depth understanding of the chemical reaction dynamics of complex 2D or quasi-2D perovskites and their electronic structures and energy band structures at their interfaces.
Figure 1 Schematic diagram of chemical and electronic structure of perovskite surface and interface
Based on PEA+ heat treatment idea, The Cs0.18FA0.82PbI3 perovskite solar cell prepared by the research team of Peking University, , has a photoelectric conversion efficiency of more than 23%, which is close to the best record of the same type of battery . The organic photoelectronics research group of Yunnan University used the latest vacuum interconnection-in-situ photoelectron spectroscopy system to study the chemical and electronic structure of PEA+ organic ligands on the surface of Cs0.18FA0.82PbI3 perovskite. in situ XPS characterization found that the physically adsorbed organic ligands on the perovskite surface volatilize with the increase of the annealing temperature of . After heating to 100°C, the halogen element cleaves from the organic ligand, while the organic cations are anchored to the perovskite surface. This cationic anchoring causes the Fermi level of the perovskite material to move upwards and forms n-type doping on the perovskite surface. Thermal evaporation-in-situ photoelectron spectroscopy test further confirms that this thermally anchored perovskite forms a barrier-free charge transport with the charge transport layer. The above results show that PEA+ anchoring on the perovskite surface is conducive to forming a good band arrangement and stabilizing the perovskite surface, which can greatly increase the working life of the device.
Figure 2 Schematic diagram of vacuum interconnection-in-situ photoelectron spectroscopy test system
The team led by Academician Lu Zhenghong has been engaged in the research of organic photoelectric materials and devices, device physics, and interface physics. Since 2022, a series of scientific research results have been published in internationally renowned journals such as Advanced Materials (IF=32.086), Advanced Optical Materials (IF=10.050), Applied Physics Letters (IF=3.971), Communications Materials (Nature Series New Journal). The research work of the team has been supported by the National Joint Research Center for Optoelectronic Energy Materials, the Key Laboratory of Optoelectronic Device Engineering of Yunnan Higher Education Institutions, and the construction of double first-class disciplines at Yunnan University.
Source: Yunnan University
Attached related links:
https://www.doi.org/10.1002/adma.202208178
https://www.doi .org/10.1002/adom.202102809
https://www.doi.org/10.1063/5.0084140
https://www.doi.org/10.1038/s43246-022-00262-2
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