High‐performance photodetectors operating over a broad wavelength range from ultraviolet, visible, to infrared are of scientific and technological importance for a wide range of applications. Here, a photodetector based on van der Waals heterostructures of graphene and its fluorine‐functionalized derivative is presented. It consistently shows broadband photoresponse from the ultraviolet (255 nm) to the mid‐infrared (4.3 µm) wavelengths, with three orders of magnitude enhanced responsivity compared to pristine graphene photodetectors. The broadband photodetection is attributed to the synergistic effects of the spatial nonuniform collective quantum confinement of sp2domains, and the trapping of photoexcited charge carriers in the localized states in sp3domains. Tunable photoresponse is achieved by controlling the nature of sp3sites and the size and fraction of sp3/sp2domains. In addition, the photoresponse due to the different photoexcited‐charge‐carrier trapping times in sp2and sp3nanodomains is determined. The proposed scheme paves the way toward implementing high‐performance broadband graphene‐based photodetectors.
Photodetectors that are intimately interfaced with human skin and measure real‐time optical irradiance are appealing in the medical profiling of photosensitive diseases. Developing compliant devices for this purpose requires the fabrication of photodetectors with ultraviolet (UV)‐enhanced broadband photoresponse and high mechanical flexibility, to ensure precise irradiance measurements across the spectral band critical to dermatological health when directly applied onto curved skin surfaces. Here, a fully 3D printed flexible UV‐visible photodetector array is reported that incorporates a hybrid organic‐inorganic material system and is integrated with a custom‐built portable console to continuously monitor broadband irradiance in‐situ. The active materials are formulated by doping polymeric photoactive materials with zinc oxide nanoparticles in order to improve the UV photoresponse and trigger a photomultiplication (PM) effect. The ability of a stand‐alone skin‐interfaced light intensity monitoring system to detect natural irradiance within the wavelength range of 310–650 nm for nearly 24 h is demonstrated.
more » « less- NSF-PAR ID:
- 10370979
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Science
- Volume:
- 9
- Issue:
- 25
- ISSN:
- 2198-3844
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
-
null (Ed.)Emerging infrared photodetectors have reported a high level of gain using trap-assisted photomultiplication mechanisms enabling significant enhancements in their sensitivity. This work investigates a series of interfacial materials in order to understand how charge blocking layers facilitate trap-assisted photomultiplication in organic shortwave infrared detectors. The hole blocking layers induce accumulation of photogenerated holes at the interface, which in turn lowers the electron injection barrier and enables photomultiplication. In addition to examining photoresponse characteristics, the device dark current is analyzed by fitting to a charge injection model to quantify injection barriers. This demonstrates that the electric field induced barrier lowering effect plateaus with increasing applied bias. Among the interfaces studied, the best detectivity is observed using the hole blocking layer bathophenanthroline (Bphen), which reduces the probability of recombination and extends the lifetime of trapped holes to increase photomultiplication. This leads to a responsivity of 5.6 A W −1 (equivalent external quantum efficiency = 660% at 1050 nm) and detectivity of 10 9 Jones with broadband operation from 600 nm to 1400 nm.more » « less
-
more » « less
Abstract Many recently developed classes of wireless, skin‐interfaced bioelectronic devices rely on conventional thermoset silicone elastomer materials, such as poly(dimethylsiloxane) (PDMS), as soft encapsulating structures around collections of electronic components, radio frequency antennas and, commonly, rechargeable batteries. In optimized layouts and device designs, these materials provide attractive features, most prominently in their gentle, noninvasive interfaces to the skin even at regions of high curvature and large natural deformations. Past studies, however, overlook opportunities for developing variants of these materials for multimodal means to enhance the safety of the devices against failure modes that range from mechanical damage to thermal runaway. This study presents a self‐healing PDMS dynamic covalent matrix embedded with chemistries that provide thermochromism, mechanochromism, strain‐adaptive stiffening, and thermal insulation, as a collection of attributes relevant to safety. Demonstrations of this materials system and associated encapsulation strategy involve a wireless, skin‐interfaced device that captures mechanoacoustic signatures of health status. The concepts introduced here can apply immediately to many other related bioelectronic devices.
-
more » « less
Abstract Indwelling arterial lines, the clinical gold standard for continuous blood pressure (BP) monitoring in the pediatric intensive care unit (PICU), have significant drawbacks due to their invasive nature, ischemic risk, and impediment to natural body movement. A noninvasive, wireless, and accurate alternative would greatly improve the quality of patient care. Recently introduced classes of wireless, skin‐interfaced devices offer capabilities in continuous, precise monitoring of physiologic waveforms and vital signs in pediatric and neonatal patients, but have not yet been employed for continuous tracking of systolic and diastolic BP—critical for guiding clinical decision‐making in the PICU. The results presented here focus on materials and mechanics that optimize the system‐level properties of these devices to enhance their reliable use in this context, achieving full compatibility with the range of body sizes, skin types, and sterilization schemes typically encountered in the PICU. Systematic analysis of the data from these devices on 23 pediatric patients, yields derived, noninvasive BP values that can be quantitatively validated against direct recordings from arterial lines. The results from this diverse cohort, including those under pharmacological protocols, suggest that wireless, skin‐interfaced devices can, in certain circumstances of practical utility, accurately and continuously monitor BP in the PICU patient population.
-
Heterojunction nanohybrids based on low-dimension semiconductors, including colloidal quantum dots (QDs) and 2D atomic materials (graphene, transition metal chalcogenides, etc) provide a fascinating platform to design of new photonic and optoelectronic devices that take advantages of the enhanced light-solid interaction attributed to their strong quantum confinement and superior charge mobility for uncooled photodetectors with a high gain up to 1010. In these heterojunction nanohybrids, the van der Waals (vdW) interface plays a critical role in controlling the optoelectronic process including exciton dissociation by the interface built-in field that drives the follow-up charge injection and transport to graphene. In this paper, we present our recent progress in development of such heterostructures nanohybrids for uncooled infrared detectors including PbS and FeS2 QDs/graphene and 2D vdW heterostructures MoTe2/Graphene/SnS2 and GaTe/InSe. We have found that nonstoichiometric Fe1–xS2 QDs (x = 0.01–0.107) with strong localized surface plasmonic resonance (LSPR) can have much enhanced absorption in broadband from ultraviolet to short-wave infrared (SWIR, 1–3 μm). Consequently, the LSPR Fe1–xS2 QDs/graphene heterostructure photodetectors exhibit extraordinary photoresponsivity in exceeding 4.32 ×106 A/W and figure-of-merit detectivity D* < 7.50 ×1012 Jones in the broadband of UV–Vis–SWIR at room temperature. The 2D vdW heterostructures allows novel designs of interface band alignments with uncooled NIR-SWIR D* up to 1012 Jones. These results illustrate that the heterostructure nanohybrids provide a promising pathway for low-cost, printable and flexible infrared detectors and imaging systems.more » « less
