Nanostructure photodetectors, as the core component of optoelectronic devices, are mainly focused on the precise preparation of mixed-component nano-heterostructures and the realization of zero power consumption devices. Herein, we successfully fabricated n-GaN/p-ZnTe core/shell nanopillar array and realized self-power ultraviolet/violet photodetection. The radial heterojunction nanodevice reveals high light-dark current ratio of 10⁴ at 0 V bias, indicating effective carriers’ separation. And more, by integrating plasmonic effect, the responsivity and detectivity of the Au nanoparticles decorated device are increased from 3.85 to 148.83 mA/W and 4.45×10¹¹ to 2.33 × 10¹² Jones under 325 nm UV light irradiation. While the rise and the fall time are decreased 1.3 times and 6.8 times under 520 nm visible light irradiation at 0 V bias. The high photocurrent gain is derived from that the oscillating high-energy hot electrons in Au nanoparticles spontaneously inject into the ZnTe conduction band to involve the photodetection process. This work presents an effective route to prepare high-performance self-power photodetector and provides a promising blueprint to realize different functional photoelectronic devices based on core/shell nanostructure.

van der Waals heterostructures (vdWHs) based on two-dimensional (2D) materials without the crystal lattice matching constraint have great potential for high-performance optoelectronic devices. Herein, a WS₂/InSe vdWH photodiode is proposed and fabricated by precisely stacking InSe and WS₂ flakes through an all-dry transfer method. The WS₂/InSe vdWH forms an n–n heterojunction with strong built-in electric field due to their intrinsic n-type semiconductor characteristics and energy-band alignments with a large Fermi level offset between WS₂ and InSe. As a result, the device displays excellent photovoltaic behavior with a large open voltage of 0.47 V and a short-circuit current of 11.7 nA under 520 nm light illumination. Significantly, a fast rising/decay time of 63/76 μs, a large light on/off ratio of 10⁵, a responsivity of 61 mA/W, a high detectivity of 2.5 × 10¹¹ Jones, and a broadband photoresponse ranging from ultraviolet to near-infrared (325–980 nm) are achieved at zero bias. This study provides a strategy for developing high-performance self-powered broadband photodetectors based on 2D materials.

Two-photon fluorescence (TPF) ellipsoid formed by a focused femtosecond laser into luminescent media serves as a fundamental pixel for TPF spatiotemporal imaging. Visualizing spatiotemporal evolution of the TPF ellipsoid itself in a selected luminescent medium is important for correctly reconstructing and interpreting spatiotemporal information of imaged targets. Here, we report a new spatiotemporal sectioning technique with a luminescent CsPbBr₃ nanosheet and visualize the spatiotemporal evolution of TPF ellipsoid along the axial direction. Time-resolved axial lengths of TPF ellipsoids turn out to broaden nonlinearly with a turning point at about 600 ps. By comparison experiments, observed phenomena are attributed to photocarrier trapping and TPF photon recycling processes within CsPbBr₃ nanosheets. The spatiotemporal sectioning technique is expected to be widely applicable, which will ignite a plethora of investigations and applications utilizing TPF ellipsoid.

Collaborative enhancements from surface plasmons (SPs) and whispering-gallery modes (WGMs) can induce intense near-field effects with high spatial localization around the surface of a semiconducting material. One can construct a highly efficient hybrid microcavity using semiconducting materials through resonant coupling between SPs and WGMs. Hexagonal ZnO micro-/nanostructures, which have been employed as natural WGM microcavities for ultraviolet (UV) lasing, can be used as ideal platforms to construct such hybrid microcavities. Here, we comprehensively review the recent efforts for improving lasing performance by resonant coupling between SPs and WGMs. Traditional SPs originating from various metals as well as novel SPs originating from atomic layers such as graphene are considered. Moreover, we discuss the mechanism of light-matter interactions beyond the improvements in lasing performance.

It is essential to develop a single mode operation and improve the performance of lasing in order to ensure practical applicability of microlasers and nanolasers. In this paper, two hexagonal microteeth with varied nanoscaled air-gaps of a ZnO microcomb are used to construct coupled whispering-gallery cavities. This is done to achieve a stable single mode lasing based on Vernier effect without requiring any complicated or sophisticated manipulation to achieve positioning with nanoscale precision. Optical gain and the corresponding ultraviolet lasing performance were improved greatly through coupling with localized surface plasmons of Pt nanoparticles. The ZnO/Pt hybrid microcavities achieved a seven-fold enhancement of intensity of single mode lasing with higher side- mode suppression ratio and lower threshold. The mechanism that led to this enhancement has been described in detail.

Collective oscillations of free electrons generate plasmons on the surface of a material. A whispering-gallery microcavity effectively confines the light field on its surface based on the total reflection from its internal wall. When these two kinds of electromagnetic waves meet each other, the stimulated emissions from an individual ZnO microrod were enhanced more than 50-fold and the threshold was reduced after the whispering-gallery microcavity was coated with a monolayer of graphene and Al nanoparticles. The improvement of the lasing performance was attributed to the synergistic energy coupling of the graphene/Al surface plasmons with ZnO excitons. The lasing characteristics and the coupling mechanism were investigated systematically.