By Dr Silpaja Chandrasekar, PhDReviewed by Lexie CornerDec 18 2024Black phosphorus (BP) is a unique allotrope of phosphorus with a layered, two-dimensional structure similar to graphite. Its puckered honeycomb lattice gives it distinct electronic and optical properties. The weak bonding between layers allows it to be easily exfoliated into ultra-thin sheets.
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This material has gained attention for its potential in electronics, optoelectronics, and energy storage. Its tunable bandgap and high carrier mobility make it a versatile option for designing nanoelectronic devices. Additionally, its properties can be adjusted by varying the number of layers, allowing for a wide range of technological applications.1
What Are the Properties of Black Phosphorus?
BP is a conductive material with properties that make it suitable for electronic applications. Its energy barrier, which ranges from 0.3 to 2 eV depending on the number of layers, can be adjusted to tailor its electronic behavior for specific uses, such as in transistors.
BP has strong anisotropic thermal and electrical properties, meaning its behavior changes depending on direction. This makes it useful for applications where precise directional control of heat or electricity is needed. Additionally, its chemical reactivity expands its potential for use in catalysis, energy storage, environmental sensing, and battery technology.2
The mechanical properties of BP, particularly in its monolayer form (phosphorene), also show anisotropy due to its puckered structure. For example, its stiffness, measured by Young’s modulus, is higher in the zigzag direction (58–89 GPa) than in the armchair direction (27–43 GPa). It can also handle a significant amount of stretching, with a tensile strain limit of up to 30 % in the armchair direction.
Environmental conditions influence these properties; for instance, exposure to oxidation can reduce the Young’s modulus from 46 GPa in a vacuum to 30 GPa. Unlike some other 2D materials, BP’s mechanical strength is less affected by grain boundaries, giving it an edge in practical applications.3
In photodetectors, BP’s tunable properties make it adaptable for detecting specific wavelengths of light, making it a good choice for high-performance photodiodes. Its anisotropic electrical behavior enhances both sensitivity and speed, while its flexibility makes it suitable for thin, bendable optical systems.4
How is Black Phosphorus Made?
BP can be synthesized using several methods, each with advantages depending on the scale and purpose of production.
Mechanical exfoliation is a widely used technique in laboratory settings, where individual monolayers are peeled from bulk BP crystals. This approach produces high-quality monolayers, making it ideal for research and characterization purposes. However, it is limited in scalability, which makes it less practical for industrial-scale applications.
For larger-scale production, chemical vapor deposition (CVD) is often used. This process deposits BP onto a substrate by introducing a phosphorus-containing gas at high temperatures. CVD enables the production of high-quality BP films with controlled thickness and crystallinity, which is essential for device fabrication. Additionally, the method offers flexibility, allowing BP to be integrated into various substrates for creating versatile, high-performance devices.5
Ink-Jet Printing of Graphene-Like Materials
Another scalable production method is liquid-phase exfoliation, where BP is dispersed in a solvent to produce thin sheets. This approach efficiently generates large quantities of BP in solution, making it suitable for applications in energy storage, sensors, and composite materials.
The process can be fine-tuned to adjust the number of layers and properties of BP, providing versatility for different uses. Liquid-phase exfoliation also improves the dispersion of BP in composite materials, enhancing the performance of the final product.6
Applications of Black Phosphorus
Electronics: BP is used in transistors, photodetectors, and flexible circuits due to its high carrier conductivity and adjustable bandgap. These features make it well-suited for advanced electronic devices, such as field-effect transistors (FETs) for next-generation, low-power, high-speed electronics.7
BP-based photodetectors are known for their excellent sensitivity, and its flexibility enables the development of stretchable and bendable circuits for wearable and flexible electronic devices.8
Optoelectronics: The optical properties of BP support its use in photonic devices and infrared sensors. For example, BP-based mid-infrared photodetectors are used in gas sensing and environmental monitoring because of their tunable bandgap and strong light absorption in the mid-infrared range.9
This opens the door for advanced optoelectronic services, including communication systems and environmental monitoring.
Energy storage: BP is used as an anode material in lithium-ion and sodium-ion batteries. Its high conductivity and large surface area enable efficient charge and discharge cycles, enhancing battery performance.
In lithium-ion batteries, BP offers a high theoretical capacity of approximately 2596 mAh/g and excellent electrical conductivity, which improve energy storage efficiency. Its layered structure supports fast ion diffusion, making it a promising option for next-generation energy storage systems.10/p>
Biomedical: BP is being explored for its potential in drug delivery and bioimaging. Its large surface area and chemical reactivity allow it to be engineered for targeted drug delivery, enabling precise therapeutic applications and minimizing side effects.
In bioimaging, BP’s properties provide high precision for visualizing cellular processes, making it a promising material for personalized medicine and advanced therapeutic innovations. These capabilities demonstrate BP’s potential to support advancements in healthcare technologies.11
Challenges and Opportunities for Future Development
One of the primary challenges with BP is its environmental instability, particularly its tendency to oxidize when exposed to air. This degradation occurs quickly under ambient conditions, limiting its long-term usability and performance in practical applications. To address this, BP devices often require protective coatings or must operate in controlled environments to prevent oxidation and preserve their functional properties.
Another challenge is scaling up the production and integration of BP into devices. While techniques like CVD and liquid-phase exfoliation can produce BP, achieving large-scale production with consistent quality remains difficult.
Incorporating BP into functional devices also requires resolving issues related to material uniformity, stability, and compatibility with other components. Developing efficient, cost-effective methods to scale production while maintaining quality is essential for BP’s broader use in commercial applications.13
Despite these challenges, black phosphorus continues to hold potential for future applications. Current research is focused on improving its stability and scalability through techniques such as encapsulation and surface functionalization to mitigate environmental degradation. Efforts are also being made to refine synthesis methods for more consistent and large-scale production.
BP’s unique properties are driving exploration into a range of applications. In quantum computing, its potential for qubit development is under investigation, while its high surface-to-volume ratio makes it suitable for water purification and gas sensing technologies in environmental science. As research advances, black phosphorus may contribute to a variety of fields, including efficient electronics and medical innovations, reinforcing its value as a versatile material in scientific and technological development.
Recent Progress on Stability and Passivation of Black Phosphorus
References and Further Reading
1. Zhang, G., Huang, S., Chaves, A., Yan, H. (2023). Black Phosphorus as Tunable Van der Waals Quantum Wells with High Optical Quality. ACS Nano, 17:6, 6073–6080. DOI: 10.1021/acsnano.3c00904, https://pubs.acs.org/doi/abs/10.1021/acsnano.3c00904
2. Lv, F., Wang, W., Li, J., Gao, Y., Wang, K. (2023). A brief review of tribological properties for black phosphorus. Friction. DOI: 10.1007/s40544-023-0758-2, https://link.springer.com/article/10.1007/s40544-023-0758-2
3. Galluzzi, M., et al. (2020). Mechanical properties and applications of 2D black phosphorus. 128:23, 230903–230903. DOI: 10.1063/5.0034893, https://pubs.aip.org/aip/jap/article/128/23/230903/288258
4. Ren, X., et al. (2017). Environmentally Robust Black Phosphorus Nanosheets in Solution: Application for Self-Powered Photodetector. Advanced Functional Materials, 27:18, 1606834. DOI: 10.1002/adfm.201606834, https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.201606834
5. Zhao, H. (2023). Black Phosphorus Nanosheets: Synthesis and Biomedical Applications. Journal of Physics Conference Series, 2566:1, 012015–012015. DOI: 10.1088/1742-6596/2566/1/012015, https://iopscience.iop.org/article/10.1088/1742-6596/2566/1/012015/meta
6.Qiao, J., et al. (2024). Controllable preparation of black phosphorus nanomaterials via liquid-phase pulsed discharge. Materials Today Chemistry, 37, 102034. DOI: 10.1016/j.mtchem.2024.102034, https://www.sciencedirect.com/science/article/abs/pii/S246851942400140X
7. Pon, A., et al. (2021). Recent Developments in Black Phosphorous Transistors: A Review. Journal of Electronic Materials, 50:11, 6020–6036. DOI: 10.1007/s11664-021-09183-1, https://link.springer.com/article/10.1007/s11664-021-09183-1
8. Zhang, F., et al. (2021). Bandgap Modulation in BP Field Effect Transistor and Its Applications. Advanced Electronic Materials, 7:8. DOI: 10.1002/aelm.202100228, https://onlinelibrary.wiley.com/doi/abs/10.1002/aelm.202100228
9. Singh Yadav, SN., et al. (2023). Plasmonic Metasurface Integrated Black Phosphorus-Based Mid-Infrared Photodetector with High Responsivity and Speed. Advanced Materials Interfaces, 10:10, 2202403. DOI: 10.1002/admi.202202403, https://onlinelibrary.wiley.com/doi/full/10.1002/admi.202202403
10. Sun, W.-C., et al. (2021). Two-dimensional metallic BP as anode material for lithium-ion and sodium-ion batteries with unprecedented performance. Journal of Materials Science, 56:24, 13763–13771. DOI: 10.1007/s10853-021-06174-9, https://link.springer.com/article/10.1007/s10853-021-06174-9
11. Li, H., et al. (2023). Research progress on black phosphorus hybrids hydrogel platforms for biomedical applications. Journal of Biological Engineering, 17:1. DOI: 10.1186/s13036-023-00328-w, https://link.springer.com/article/10.1186/s13036-023-00328-w
12. Zhang, G., et al. (2023). A review on black-phosphorus-based composite heterojunction photocatalysts for energy and environmental applications. Separation and Purification Technology, 307, 122833. DOI: 10.1016/j.seppur.2022.122833, https://www.sciencedirect.com/science/article/abs/pii/S1383586622023905
13. Kishore, SC., et al. (2024). A critical review on black phosphorus and its utilization in the diverse range of sensors. Sensors and Actuators A: Physical, 377, 115719. DOI: 10.1016/j.sna.2024.115719, https://www.sciencedirect.com/science/article/abs/pii/S0924424724007131
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