Real-Time and Highly Sensitive Sub-Wavelength 2D Hybrid Perovskite Photodetectors and Sensors for Environmental and Healthcare Monitoring

Layered (2D) perovskites, known for their enhanced stability under ambient conditions compared to their 3D bulk counterparts, are gaining significant attention due to their highly tuneable optical and electrical properties. This has sparked considerable interest in their potential for advanced 2D-photovoltaic applications. However, the full value of 2D hybrid perovskites in nano-scale optoelectronics has remained underexplored, primarily due to their sensitivity to environmental conditions and the solvents used in conventional semiconductor fabrication processes. This has posed challenges in developing competitive perovskite-based solutions for high-density and large bandwidth signal processing.<br/>In this presentation, we showcase our development of nano-scale 2D-fluorinated phenethylammonium lead iodide perovskite (F-PEAI) planar photodetectors [1,2]. Remarkably, these devices are entirely fabricated under ambient conditions using standard electron beam lithography that involves solvents. Our photodetectors exhibit exceptional performance metrics, including a room temperature detectivity exceeding 5 × 10^17 Jones, a real-time photoresponse comparable to commercial 2 GHz Si photodiodes, an extraordinarily large linear dynamic range of 228 dB, and a photo-responsivity of approximately 1100 A/W. Notably, these devices maintain stability from room temperature down to 4 K and can be reliably fabricated on diverse substrates, including flexible and wearable media, without performance loss. This is a significant advantage over other 2D materials, such as graphene and transition metal dichalcogenides, which require planarization and atomically clean dielectrics.<br/>Furthermore, we demonstrate the successful fabrication of planar nano-scale 2D F-PEAI photodetectors with sub-wavelength dimensions, smaller than one-fifth the wavelength of the detected light. This breakthrough opens new possibilities for high-definition imaging technologies using perovskites.[1]<br/>Expanding on this innovation, we also explore the potential of 2D F-PEAI for sensing applications in aqueous environments [2]. By utilizing the unique properties of natural beeswax as a protective encapsulation layer, we have developed photodetectors with outstanding performance, including responsivity greater than 2200 A/W and detectivity of 2.4 × 10^18 Jones. The hydrophobic beeswax coating grants these sensors exceptional durability against prolonged immersion in contaminated water, extending the operational lifespan to over one year. Additionally, the biocompatibility and self-cleaning attributes of beeswax enable the same sensors to be effectively used for healthcare applications, such as monitoring human heartbeat through photoplethysmography, capturing clear systolic and diastolic signals.<br/>The remarkable combination of ambient stability and exceptional optoelectronic properties of 2D F-PEAI, coupled with innovative beeswax encapsulation, heralds a new era of opportunities for multipurpose applications in sustainable electronics. Our work paves the way for the versatile and practical use of 2D perovskites in both environmental and healthcare monitoring, underscoring their significant potential in addressing key societal challenges.<br/><br/><br/>References:<br/>[1] R. Mastria, K. J. Riisnaes, A. Bacon, I. Leontis, H. T. Lam, M. A. S. Alshehri, D. Colridge, T. H. E. Chan, A. De Sanctis, L. De Marco, L. Polimeno, A. Coriolano, A. Moliterni, V. Olieric, C. Giannini, S. Hepplestone, M. F. Craciun, S. Russo, Real Time and Highly Sensitive Sub-Wavelength 2D Hybrid Perovskite Photodetectors. <i>Advanced Functional Materials</i> 2024, 2401903. https://doi.org/10.1002/adfm.202401903<br/>[2] K. J. Riisnaes, M. Alshehri, I. Leontis, R. Mastria, H. T. Lam, L. De Marco, A. Coriolano, M. F. Craciun, S. Russo, 2D Hybrid Perovskite Sensors for Environmental and Healthcare Monitoring. <i>ACS Applied Materials and Interfaces</i> 2024, https://doi.org/10.1021/acsami.4c02966.