Defect-Induced Modulation of Electronic and Optical Properties in Monolayer CsPb<sub>2</sub>Br<sub>5</sub>: Implications for Fiber-Optic Sensing Applications
Two−dimensional halide perovskites have emerged as promising optoelectronic materials, yet the uncontrolled defect formation during synthesis remains a critical challenge for their practical applications. In this work, we systematically investigate the structural, electronic, and optical properties...
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2025-06-01
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| author | Meiqi An Wenxuan Fan Shengsheng Wei Junqiang Wang |
| author_facet | Meiqi An Wenxuan Fan Shengsheng Wei Junqiang Wang |
| author_sort | Meiqi An |
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| description | Two−dimensional halide perovskites have emerged as promising optoelectronic materials, yet the uncontrolled defect formation during synthesis remains a critical challenge for their practical applications. In this work, we systematically investigate the structural, electronic, and optical properties of monolayer CsPb<sub>2</sub>Br<sub>5</sub> in two representative configurations: ds−CsPb<sub>2</sub>Br<sub>5</sub> and ss−CsPb<sub>2</sub>Br<sub>5</sub>. By introducing four types of vacancy defects—V<sub>Br−c</sub>, V<sub>Br−b</sub>, V<sub>Cs</sub>, and V<sub>Pb</sub>, we analyze their structural distortions, formation energies, and their impact on band structure and optical response using first−principles calculations. Our results reveal that Br−related vacancies are energetically most favorable and induce shallow defect levels and absorption edge redshifts in the ds−CsPb<sub>2</sub>Br<sub>5</sub> structure, while in the ss−CsPb<sub>2</sub>Br<sub>5</sub> configuration, only V<sub>Br−b</sub> forms a defect state. V<sub>Pb</sub> and V<sub>Cs</sub> lead to significant sub−bandgap absorption enhancement and dielectric response due to band−edge reorganization, despite not introducing in−gap states. Notably, V<sub>Br−c</sub> exhibits distinct infrared absorption in the ss−CsPb<sub>2</sub>Br<sub>5</sub> model without electronic trap formation. These findings underscore the critical influence of defect type and slab asymmetry on the optoelectronic behavior of CsPb<sub>2</sub>Br<sub>5</sub>, providing guidance for defect engineering in perovskite−based optoelectronic applications. |
| format | Article |
| id | doaj-art-382fd82d33a44efb8673807cf3b27bbf |
| institution | DOAJ |
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| language | English |
| publishDate | 2025-06-01 |
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| series | Photonics |
| spelling | doaj-art-382fd82d33a44efb8673807cf3b27bbf2025-08-20T03:08:02ZengMDPI AGPhotonics2304-67322025-06-0112763810.3390/photonics12070638Defect-Induced Modulation of Electronic and Optical Properties in Monolayer CsPb<sub>2</sub>Br<sub>5</sub>: Implications for Fiber-Optic Sensing ApplicationsMeiqi An0Wenxuan Fan1Shengsheng Wei2Junqiang Wang3School of Integrated Circuits, Dalian University of Technology, Dalian 116024, ChinaSchool of Semiconductor and Physics, North University of China, Taiyuan 030051, ChinaSchool of Semiconductor and Physics, North University of China, Taiyuan 030051, ChinaSchool of Instrument and Electronics, North University of China, Taiyuan 030051, ChinaTwo−dimensional halide perovskites have emerged as promising optoelectronic materials, yet the uncontrolled defect formation during synthesis remains a critical challenge for their practical applications. In this work, we systematically investigate the structural, electronic, and optical properties of monolayer CsPb<sub>2</sub>Br<sub>5</sub> in two representative configurations: ds−CsPb<sub>2</sub>Br<sub>5</sub> and ss−CsPb<sub>2</sub>Br<sub>5</sub>. By introducing four types of vacancy defects—V<sub>Br−c</sub>, V<sub>Br−b</sub>, V<sub>Cs</sub>, and V<sub>Pb</sub>, we analyze their structural distortions, formation energies, and their impact on band structure and optical response using first−principles calculations. Our results reveal that Br−related vacancies are energetically most favorable and induce shallow defect levels and absorption edge redshifts in the ds−CsPb<sub>2</sub>Br<sub>5</sub> structure, while in the ss−CsPb<sub>2</sub>Br<sub>5</sub> configuration, only V<sub>Br−b</sub> forms a defect state. V<sub>Pb</sub> and V<sub>Cs</sub> lead to significant sub−bandgap absorption enhancement and dielectric response due to band−edge reorganization, despite not introducing in−gap states. Notably, V<sub>Br−c</sub> exhibits distinct infrared absorption in the ss−CsPb<sub>2</sub>Br<sub>5</sub> model without electronic trap formation. These findings underscore the critical influence of defect type and slab asymmetry on the optoelectronic behavior of CsPb<sub>2</sub>Br<sub>5</sub>, providing guidance for defect engineering in perovskite−based optoelectronic applications.https://www.mdpi.com/2304-6732/12/7/638perovskitesCsPb<sub>2</sub>Br<sub>5</sub>vacancy defectsoptoelectronic |
| spellingShingle | Meiqi An Wenxuan Fan Shengsheng Wei Junqiang Wang Defect-Induced Modulation of Electronic and Optical Properties in Monolayer CsPb<sub>2</sub>Br<sub>5</sub>: Implications for Fiber-Optic Sensing Applications Photonics perovskites CsPb<sub>2</sub>Br<sub>5</sub> vacancy defects optoelectronic |
| title | Defect-Induced Modulation of Electronic and Optical Properties in Monolayer CsPb<sub>2</sub>Br<sub>5</sub>: Implications for Fiber-Optic Sensing Applications |
| title_full | Defect-Induced Modulation of Electronic and Optical Properties in Monolayer CsPb<sub>2</sub>Br<sub>5</sub>: Implications for Fiber-Optic Sensing Applications |
| title_fullStr | Defect-Induced Modulation of Electronic and Optical Properties in Monolayer CsPb<sub>2</sub>Br<sub>5</sub>: Implications for Fiber-Optic Sensing Applications |
| title_full_unstemmed | Defect-Induced Modulation of Electronic and Optical Properties in Monolayer CsPb<sub>2</sub>Br<sub>5</sub>: Implications for Fiber-Optic Sensing Applications |
| title_short | Defect-Induced Modulation of Electronic and Optical Properties in Monolayer CsPb<sub>2</sub>Br<sub>5</sub>: Implications for Fiber-Optic Sensing Applications |
| title_sort | defect induced modulation of electronic and optical properties in monolayer cspb sub 2 sub br sub 5 sub implications for fiber optic sensing applications |
| topic | perovskites CsPb<sub>2</sub>Br<sub>5</sub> vacancy defects optoelectronic |
| url | https://www.mdpi.com/2304-6732/12/7/638 |
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