Bowen Du

Abstract Ultraviolet (UV) photodetectors with high responsivity and fast response are crucial for practical applications. Double perovskite Cs 2 AgBiBr 6 has emerged as a promising optoelectronic material due to its excellent physics and photoelectric properties. However, no work is reported based on its film for photodetector applications. Herein, an ITO/SnO 2 /Cs 2 AgBiBr 6 /Au hole‐transport layer free planar heterojunction device is fabricated for photodetector application. The device is self‐powered with two responsivity peaks at 350 and 435 nm, which is suitable for ultraviolet‐A (320–400 nm) and deep‐blue light detecting. A high responsivity of 0.11 A W −1 at 350 nm and a quick response time of less than 3 ms are obtained, which is significantly higher than other semiconductor oxide heterojunction‐based UV detectors. More importantly, the stability is significantly better than most of the hybrid perovskite photodetectors reported so far. Its photocurrent shows no obvious degradation after more than 6 months storage in ambient conditions without any encapsulation. Consequently, the utilization of Cs 2 AgBiBr 6 film is a practical approach for high performance, large‐area lead‐free perovskite photodetector applications. For the mechanism, it is found that photogenerated carriers in Cs 2 AgBiBr 6 film are separated at the Cs 2 AgBiBr 6 /SnO 2 heterojunction interface by its built‐in field. The low toxicity and high stability of this double perovskite active layer make it very promising for practical applications.

Abstract Achieving strong coupling between plasmonic oscillators can significantly modulate their intrinsic optical properties. Here, we report the direct observation of ultrafast plasmonic hot electron transfer from an Au grating array to an MoS 2 monolayer in the strong coupling regime between localized surface plasmons (LSPs) and surface plasmon polaritons (SPPs). By means of femtosecond pump-probe spectroscopy, the measured hot electron transfer time is approximately 40 fs with a maximum external quantum yield of 1.65%. Our results suggest that strong coupling between LSPs and SPPs has synergetic effects on the generation of plasmonic hot carriers, where SPPs with a unique nonradiative feature can act as an ‘energy recycle bin’ to reuse the radiative energy of LSPs and contribute to hot carrier generation. Coherent energy exchange between plasmonic modes in the strong coupling regime can further enhance the vertical electric field and promote the transfer of hot electrons between the Au grating and the MoS 2 monolayer. Our proposed plasmonic strong coupling configuration overcomes the challenge associated with utilizing hot carriers and is instructive in terms of improving the performance of plasmonic opto-electronic devices.

2D transition metal dichalcogenides are becoming attractive materials for novel photoelectric and photovoltaic applications due to their excellent optoelectric properties and accessible optical bandgap in the near‐infrared to visible range. Devices utilizing 2D materials integrated with metal nanostructures have recently emerged as efficient schemes for hot electron‐based photodetection. Metal‐semiconductor heterostructures with low cost, simple procedure, and fast response time are crucial for the practical applications of optoelectric devices. In this paper, template‐based sputtering method is used first to fabricate Au nanoantenna (NA)/MoS 2 heterostructures with low cost, simple preparation, broad spectral response, and fast response time. Through the measurement of femtosecond pump‐probe spectroscopy, it is demonstrated that plasmon‐induced hot electron transfer takes place in the Au NA/MoS 2 heterostructure on the order of 200 fs with an injected electron density of about 5.6 × 10 12 cm −2 . Moreover, the pump‐power‐dependent photoluminescence spectra confirm that the exciton energy of MoS 2 can be enhanced, coupled, and reradiated by the Au NA. Such ultrafast plasmon‐induced hot electron transfer in the metal‐semiconductor heterostructure can enable novel 2D devices for light harvesting and photoelectric conversion.

Recent advances in twistronics have revealed tunable optoelectronic properties in twisted bilayer graphene (tBLG), including angle-dependent dielectric responses and enhanced light absorption due to van Hove singularity (VHS). However, achieving high photoresponsivity in tBLG-based sensors typically requires intense illumination. We present an ultrasensitive optoelectronic biosensor integrating tBLG superlattices with Au nanodisks and clustered regularly interspaced short palindromic repeat (CRISPR)-Cas12a via DNA origami. By aligning the 9.4° tBLG's VHS absorption spectrum with Au nanodisks' plasmonic resonance at 60 μW, we achieve a 7-fold photocurrent enhancement over pristine tBLG. CRISPR-Cas12a-mediated trans-cleavage dynamically modulates the local dielectric environment, enabling sub-femtomolar (44.63 attomolar, aM) nucleic acid detection without external amplification. Clinical validation using lung cancer samples shows high concordance with quantitative polymerase chain reaction (qPCR), demonstrating real-time, label-free detection of microRNA (miRNA). This hybrid platform combines moiré-engineered optoelectronics with programmable bio-nanoarrays, offering a scalable solution for precision diagnostics with ultralow detection limits and rapid response times.

The manipulation of light in an integrated circuit is crucial for the development of high-speed electro-optic devices. Recently, molybdenum disulfide (MoS2) monolayers generated broad interest for the optoelectronics because of their huge exciton binding energy, tunable optical emission, direct electronic band-gap structure, etc. Miniaturization and multifunctionality of electro-optic devices further require the manipulation of light–matter interaction at the single-nanoparticle level. The strong exciton–plasmon interaction that is generated between the MoS2 monolayers and metallic nanostructures may be a possible solution for compact electro-optic devices at the nanoscale. Here, we demonstrate a nanoplasmonic modulator in the visible spectral region by combining the MoS2 monolayers with a single Au nanodisk. The narrow MoS2 excitons coupled with broad Au plasmons result in a deep Fano resonance, which can be switched on and off by applying different gate voltages on the MoS2 monolayers. A reversible display device that is based on this single-nanoparticle modulator is demonstrated with a heptamer pattern that is actively controlled by the external gates. Our work provides a potential application for electro-optic modulation on the nanoscale and promotes the development of gate-tunable nanoplasmonic devices in the future.