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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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-06-01
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| Series: | Photonics |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2304-6732/12/7/638 |
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| Summary: | 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. |
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| ISSN: | 2304-6732 |