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Pressure‐Dependent Polymorphism and Band‐Gap Tuning of Methylammonium Lead Iodide Perovskite |
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| Authors: | Shaojie Jiang Dr. Yanan Fang Dr. Ruipeng Li Dr. Hai Xiao Jason Crowley Dr. Chenyu Wang Prof. Timothy J. White Prof. William A. Goddard III Dr. Zhongwu Wang Dr. Tom Baikie Prof. Jiye Fang |
| Affiliation: | 1. Materials Science and Engineering Program, State University of New York at Binghamton, Binghamton, NY, USA;2. Energy Research Institute@NTU (ERI@N), Nanyang Technological University, Singapore, Republic of Singapore;3. Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY, USA;4. Materials and Process Simulation Center (MSC) and Joint Center for Artificial Photosynthesis (JCAP), California Institute of Technology, Pasadena, CA, USA;5. Department of Chemistry, State University of New York at Binghamton, Binghamton, NY, USA;6. School of Materials Science and Engineering, Nanyang Technological University, Singapore, Republic of Singapore |
| Abstract: | We report the pressure‐induced crystallographic transitions and optical behavior of MAPbI3 (MA=methylammonium) using in situ synchrotron X‐ray diffraction and laser‐excited photoluminescence spectroscopy, supported by density functional theory (DFT) calculations using the hybrid functional B3PW91 with spin‐orbit coupling. The tetragonal polymorph determined at ambient pressure transforms to a ReO3‐type cubic phase at 0.3 GPa. Upon continuous compression to 2.7 GPa this cubic polymorph converts into a putative orthorhombic structure. Beyond 4.7 GPa it separates into crystalline and amorphous fractions. During decompression, this phase‐mixed material undergoes distinct restoration pathways depending on the peak pressure. In situ pressure photoluminescence investigation suggests a reduction in band gap with increasing pressure up to ≈0.3 GPa and then an increase in band gap up to a pressure of 2.7 GPa, in excellent agreement with our DFT calculation prediction. |
| Keywords: | band gap halide perovskite high-pressure chemistry phase transitions photoluminescence |