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Anion Engineering Enhanced Response Speed and Tunable Spectral Responsivity in Gallium-Oxynitrides-Based Ultraviolet Photodetectors
摘要： Most of the currently developed Ga2O3-based solar blind photodetectors exhibit unexpected high persistent photoconductive gain at the expense of low response speed, and thus, the suppression of carrier trapping remains challenging. In this work, we demonstrated amorphous gallium-oxynitride-based (GaON) ultraviolet photodetectors with tunable spectral response and enhanced response speed by in situ anion engineering with a reactive sputtering technique. The tunable spectral response from 4.95 to 4.37 eV is a result of a bandgap narrowing effect, attributed to the elevation of the valence band maximum (VBM) by the hybridization of N 2p and O 2p states and the enhanced p-d repulsion. The constructed GaON PDs with a proper nitrogen composition exhibit remarkably reduced dark current and a fast response time of about 100 μs. Oxygen vacancies are deactivated by the lift-up of VBM so that slow carrier detrapping processes are suppressed, resulting in the reduced persistent photoconductivity and improved response speed. Meanwhile, nitrogen introduction increases the recombination and scattering probabilities of photoexcited carriers, which results in the reduced photoresponsivity. Thus, the rational design through anion engineering allows a flexibility in bandgap modulation and suppression of carrier trapping in oxynitrides, which provides an alternative strategy to achieve high-speed ultraviolet photodetectors.
关键词： ultraviolet photodetectors,gallium oxynitrides,bandgap modulation,photoconductive gain,anion engineering
更新于2025-09-23 15:19:57
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Self-Powered Solar-Blind Photodetectors Based on <i>?±</i> / <i>?2</i> Phase Junction of
摘要： Self-powered Ga2O3-based solar-blind photodetectors have received attention recently due to the increased demand for energy saving, miniaturization, and high efficiency in devices. An ideal device structure consisting of a Ga2O3-based p-n junction is still difficult to obtain, since p-type doping is a major challenge. Although self-powered devices based on heterojunction are promising, there are two fatal disadvantages: (1) photosensitivity of the non-solar-blind region, on account of the narrower band gap of the heterojunction materials; and (2) poor quality of the epitaxial film due to lattice mismatch. In view of the various polymorphs of Ga2O3, we propose constructing a structure consisting of a Ga2O3 phase junction with α and β phases (α/β phase junction) for self-powered solar-blind photodetectors. The small lattice mismatch and similar band gap between α- and β-Ga2O3 will solve the two problems outlined above. The formation of α- and β-Ga2O3 is expected to result in a type-II band alignment, promoting separation of photogenerated carriers, which transfer through the junction to the corresponding electrodes. Herein, the α/β phase junction of Ga2O3 vertically aligned nanorod arrays with a thickness-controllable β-Ga2O3 shell layer are fabricated by a low-cost and simple process of hydrothermal and postannealing treatment. Two different types of self-powered α/β-Ga2O3 phase junction-based photodetectors, in the form of solid-state type and photoelectrochemical type, are constructed and realized. Our analysis shows that the constructed photodetectors are capable of highly efficient detection of solar-blind signal without any bias voltage. This work demonstrates the usefulness of using the α/β-Ga2O3 phase junction in a self-powered solar-blind photodetector, which is not only energy efficient, but also potentially workable in outer space, at the south and north pole, and other harsh environments without external power for a long time.
关键词： solar-blind photodetectors,phase junction,Ga2O3,α/β phase junction,self-powered
更新于2025-09-23 15:19:57
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Tunable Photodetectors via In Situ Thermal Conversion of TiS3 to TiO2
摘要： In two-dimensional materials research, oxidation is usually considered as a common source for the degradation of electronic and optoelectronic devices or even device failure. However, in some cases a controlled oxidation can open the possibility to widely tune the band structure of 2D materials. In particular, we demonstrate the controlled oxidation of titanium trisulfide (TiS3), a layered semiconductor that has attracted much attention recently thanks to its quasi-1D electronic and optoelectronic properties and its direct bandgap of 1.1 eV. Heating TiS3 in air above 300 °C gradually converts it into TiO2, a semiconductor with a wide bandgap of 3.2 eV with applications in photoelectrochemistry and catalysis. In this work, we investigate the controlled thermal oxidation of individual TiS3 nanoribbons and its influence on the optoelectronic properties of TiS3-based photodetectors. We observe a step-wise change in the cut-off wavelength from its pristine value ~1000 nm to 450 nm after subjecting the TiS3 devices to subsequent thermal treatment cycles. Ab-initio and many-body calculations confirm an increase in the bandgap of titanium oxysulfide (TiO2-xSx) when increasing the amount of oxygen and reducing the amount of sulfur.
关键词： TiS3,2D materials,photodetectors,DFT GW,oxidation,TiO2,Raman spectroscopy
更新于2025-09-23 15:19:57
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Flexible and Selfa??Powered Lateral Photodetector Based on Inorganic Perovskite CsPbI <sub/>3</sub> a??CsPbBr <sub/>3</sub> Heterojunction Nanowire Array
摘要： Self-powered perovskite photodetectors mainly adopt the vertical heterojunction structure composed of active layer, electron–hole transfer layers, and electrodes, which results in the loss of incident light and interfacial accumulation of defects. To address these issues, a self-powered lateral photodetector based on CsPbI3–CsPbBr3 heterojunction nanowire arrays is designed on both a rigid glass and a flexible polyethylene naphthalate substrate using an in situ conversion and mask-assisted electrode fabrication method. Through adding the polyvinyl pyrrolidone and optimizing the concentration of precursors under the pressure-assisted moulding process, both the crystallinity and stability of perovskite nanowire array are improved. The nanowire array–based lateral device shows a high responsivity of 125 mA W?1 and a fast rise and decay time of 0.7 and 0.8 ms under a self-powered operation condition. This work provides a new strategy to fabricate perovskite heterojunction nanoarrays towards self-powered photodetection.
关键词： perovskites,photodetectors,flexible devices,self-powered
更新于2025-09-23 15:19:57
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Delayed Charge Recombination by Opena??Shell Organics: Its Application in Achieving Superb Photodetectors with Broadband (400a??1160 nm) Ultrahigh Sensitivity and Stability
摘要： Monolayer transition-metal dichalcogenides have inspired worldwide efforts in optoelectronic devices but real applications are hindered with their reduced optical absorption due to their atomically ultrathin signature. In this study, by utilizing their biradical nature such as excellent absorption coefficient, broad bandwidth from the ultraviolet to near-infrared region, and small triplet–singlet energy gap, a series of helicene 5,14-diaryldiindeno[2,1-f:1′,2′-j]picene (DDP) derivatives (1ab, 1ac, and 1bb) are integrated with monolayer MoS2 for extraordinary photodetector performance and outstanding stability. Via comprehensive time-resolved studies, the interfacial charge-transfer process from the DDPs to the MoS2 layer is evidenced by the stabilized exciton property of the organics (1ac)/MoS2 heterostructure. Significantly, the 1ac/MoS2 photodetector exhibits an ultrahigh photoresponsivity of 5 × 107 A W?1 and a fast response speed of 45 ms due to the highly efficient photoexcited carrier separation and the matched type-II energy band alignment. The biradical 1ac/MoS2 hybrid photodetector shows no sign of degradation after one-month operation. The results pave a new avenue for biradical based high-performance and super-broadband optoelectronic devices.
关键词： photodetectors,hybrid structures,MoS2,biradical organic molecules,transition metal dichalcogenides
更新于2025-09-23 15:19:57
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Selfa??Powered Flexible TiO <sub/>2</sub> Fibrous Photodetectors: Heterojunction with P3HT and Boosted Responsivity and Selectivity by Au Nanoparticles
摘要： A novel inorganic–organic heterojunction (TiO2/P3HT (poly(3-hexylthiophene)) is easily prepared by a combination of anodization and vacuumed dip-coating methods, and the constructed flexible fibrous photodetector (FPD) exhibits high-performance self-powered UV–visible broadband photoresponse with fast speed, high responsivity, and good stability, as well as highly stable performance at bending states, showing great potential for wearable electronic devices. Moreover, Au nanoparticles are deposited to further boost the responsivity and selectivity by regulating the sputtering intervals. The optimal Au/TiO2/P3HT FPD yields an ≈700% responsivity enhancement at 0 V under 350 nm illumination. The sharp cut-off edge and high UV–visible rejection ratio (≈17 times higher) indicate a self-powered flexible UV photodetector. This work provides an effective and versatile route to modulate the photoelectric performance of flexible electronic devices.
关键词： TiO2/P3HT heterojunctions,Au nanoparticles,fiber photodetectors,flexible devices,self-powered
更新于2025-09-23 15:19:57
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Graphene Plasmonic Fractal Metamaterials for Broadband Photodetectors
摘要： Metamaterials have recently established a new paradigm for enhanced light absorption in state-of-the-art photodetectors. Here, we demonstrate broadband, highly efficient, polarization-insensitive, and gate-tunable photodetection at room temperature in a novel metadevice based on gold/graphene Sierpinski carpet plasmonic fractals. We observed an unprecedented internal quantum efficiency up to 100% from the near-infrared to the visible range with an upper bound of optical detectivity of 1011 Jones and a gain up to 106, which is a fingerprint of multiple hot carriers photogenerated in graphene. Also, we show a 100-fold enhanced photodetection due to highly focused (up to a record factor of |e/e0| ≈ 20 for graphene) electromagnetic fields induced by electrically tunable multimodal plasmons, spatially localized in self-similar fashion on the metasurface. Our findings give direct insight into the physical processes governing graphene plasmonic fractal metamaterials. the proposed structure represents a promising route for the realization of a broadband, compact, and active platform for future optoelectronic devices including multiband bio/chemical and light sensors.
关键词： graphene,metamaterials,plasmonic fractals,gate-tunable,photodetectors,polarization-insensitive,broadband
更新于2025-09-23 15:19:57
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High-Performance UVa??Vis Photodetectors Based on a Lead-Free Hybrid Perovskite Crystal (MV)[SbI <sub/>3</sub> Cl <sub/>2</sub> ]
摘要： Low-dimensional lead-free organic?inorganic hybrid perovskites have gained increasing attention as having low toxicity, ease of processing, and good optoelectronic properties. Seeking for lead-free and narrow band gap organic?inorganic hybrid perovskites are of great importance for the development and application of photoelectric materials. Here, we reported a Sb-based organic?inorganic hybrid perovskite (MV)[SbI3Cl2], which has one-dimensional inorganic frameworks of the I-sharing double octahedra. (MV)[SbI3Cl2] shows a narrow direct band gap of 1.5 eV, and displays obvious photoresponse for the 532 nm light with rapid response speed of trise = 0.69 s, tdecay = 0.28 s. With an illumination power of 5 mW and a 50 V bias, the responsivities (R) and external quantum e?ciency (EQE) for (MV)[SbI3Cl2] photodetector under 532 nm laser are 29.75 mA/W and 6.69% respectively. This Sb-based halide double perovskite material will provide an alternative material for photodetector devices.
关键词： organic?inorganic hybrid perovskites,Sb-based,narrow band gap,photodetectors,lead-free
更新于2025-09-23 15:19:57
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High Sensitivity Visible-Near Infrared Organic Photodetector Based on Non-fullerene Acceptor
摘要： Highly sensitive solution-processed organic photodetectors (OPDs) with a broadband response ranging from visible to near infrared (NIR) and excellent overall device performance are demonstrated. The OPDs were fabricated from a blend consisting of a wide bandgap polymer donor and a newly developed fused octacylic small-molecule electron acceptor with acceptor–donor–acceptor structure, which shows relatively high and balanced hole/electron mobility and allow for thicker photoactive layer (~300 nm). In conjunction with the use of an optimized inverted device structure, the dark current density of the OPDs was suppressed to an ultralow level of (8.3±5.5)×10-10A cm-2 at bias of –1 V and the capability to directly weak light intensity is down to 0.24 pW cm?2, both are among the lowest reported values for OPDs. Owing to the low shot noise enabled by the inverted structure and the low thermal noise due to the high shunt resistance of the device, the obtained OPDs shows spectrally flat photoresponse in the range of 350–950 nm (UV-Vis-NIR) and a maximal specific detectivity (D*) of (2.1±0.1)×1013 Jones at 800–900 nm, which is among the best results of NIR OPDs reported to date and represents a highly sensitive photodetector for weak optical signal detection. Besides, the OPDs shows a wide bandwidth of 30 kHz, fast temporal response time around 12 us ~14 us and a large linear dynamic range of 106 dB.
关键词： dark current density,specific detectivity,non-fullerene acceptors,weak optical signal detection,organic photodetectors
更新于2025-09-23 15:19:57
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Gianta??Enhanced SnS <sub/>2</sub> Photodetectors with Broadband Response through Oxygen Plasma Treatment
摘要： Layered tin disulfide (SnS2) is a vital semiconductor with versatile functionality due to its high carrier mobility and excellent photoresponsivity. However, the intrinsic defects Vs (sulfur vacancies), which cause Fermi level pinning (significant metal contact resistance), hinder its electrical and optoelectrical performance. Herein, oxygen plasma treatment is employed to enhance the optoelectronic performance of SnS2 flakes, which results in artificial sub-bandgap in SnS2. Consequently, the broadband photosensing (300–750 nm) is remarkably improved. Specifically, under 350 nm illumination, the O2-plasma-treated SnS2 photodetector exhibits an enhanced photoresponsivity from 385 to 860 A W?1, the external quantum efficiency and the detectivity improve by one order of magnitude as well as increase the photoswitching response improvement by two orders of magnitude for both rising (τr) and decay (τd) time. This artificial sub-bandgap can both improve the photoresponse and broaden the response spectra, which paves a new path for the applications of optoelectronics.
关键词： broadband photodetection,2D materials,SnS2 photodetectors,oxygen plasma treatment
更新于2025-09-23 15:19:57