3D organic-inorganic hybrid perovskites have featured high gain coefficients through the electron-hole plasma stimulated emission mechanism, while their 2D counterparts of Ruddlesden-Popper perovskites (RPPs) exhibit strongly bound electron-hole pairs (excitons) at room temperature. High-performance solar cells and light-emitting diodes (LEDs) are reported based on 2D RPPs, whereas light-amplification devices remain largely unexplored. Here, it is demonstrated that ultrafast energy transfer along cascade quantum well (QW) structures in 2D RPPs concentrates photogenerated carriers on the lowest-bandgap QW state, at which population inversion can be readily established enabling room-temperature amplified spontaneous emission and lasing. Gain coefficients measured for 2D RPP thin-films (≈100 nm in thickness) are found about at least four times larger than those for their 3D counterparts. High-density large-area microring arrays of 2D RPPs are fabricated as whispering-gallery-mode lasers, which exhibit high quality factor (Q ≈ 2600), identical optical modes, and similarly low lasing thresholds, allowing them to be ignited simultaneously as a laser array. The findings reveal that 2D RPPs are excellent solution-processed gain materials potentially for achieving electrically driven lasers and ideally for on-chip integration of nanophotonics.

Miniaturized nanowire nanolasers of 3D perovskites feature a high gain coefficient; however, room-temperature optical gain and nanowire lasers from 2D layered perovskites have not been reported to date. A biomimetic approach is presented to construct an artificial ligh-harvesting system in mixed multiple quantum wells (QWs) of 2D-RPPs of (BA) (FA) Pb Br , achieving room-temperature ASE and nanowire (NW) lasing. Owing to the improvement of flexible and deformable characteristics provided by organic BA cation layers, high-density large-area NW laser arrays were fabricated with high photostability. Well-controlled dimensions and uniform geometries enabled 2D-RPPs NWs functioning as high-quality Fabry-Perot (FP) lasers with almost identical optical modes, high quality (Q) factor (ca. 1800), and similarly low lasing thresholds.

Given that catechol and nitrite can be easily released into the environment and cause serious damage to our physical and ecological environment, it is necessary to develop a fast and reliable detection method for catechol and nitrite analysis. In our work, an electrochemical catechol and nitrite sensor was created based on gold nanoparticles (AuNPs) deposited on chitosan@N,S co-doped multiwalled carbon nanotubes (CS@N,S co-doped MWCNTS) composite modified glassy carbon electrode. The preliminary prepared composite materials were characterized by transmission electron microscope, scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The AuNPs/CS@N,S co-doped MWCNTS modified electrode shows a good linear relationship between 1 μmol·L–1 (μM) and 5000 μM for catechol, and the detection limit was calculated as 0.2 μM. For nitrite the linear relationship was 1–7000 μM with the detection limit of 0.2 μM. The sensitivity of the created sensor was evaluated as 0.9081 μA·μM–1·cm–2 for catechol, and for nitrite it was 0.7595 μA·μM–1·cm–2. Also the sensor shows significant selectivity, reproducibility, and stability. Moreover, the modified electrode is also applied in tap water samples for the catechol measurement and nitrite in fermented bean curd, ham sausage, and mustard tuber samples.

Miniaturized nanowire nanolasers of 3D perovskites feature ah igh gain coefficient;h owever,r oom-temperature optical gain and nanowire lasers from 2D layered perovskites have not been reported to date.Ab iomimetic approach is presented to construct an artificial ligh-harvesting system in mixed multiple quantum wells (QWs) of 2D-RPPs of (BA) 2 -(FA) nÀ1 Pb n Br 3n+1 ,a chieving room-temperature ASE and nanowire (NW) lasing.O wing to the improvement of flexible and deformable characteristics provided by organic BA cation layers,high-density large-area NW laser arrays were fabricated with high photostability.W ell-controlled dimensions and uniform geometries enabled 2D-RPPs NWs functioning as highquality Fabry-Perot (FP) lasers with almost identical optical modes,h igh quality (Q) factor (ca. 1800), and similarly low lasing thresholds.Ever-increasing demands on high-speed optical communication and data processing had stimulated ag reat deal of research interest in nanophotonics. [1] Semiconductor nanowire (NW) lasers are promising as miniaturized building blocks for on-chip integration of photonic circuits,o wing to their ultra-compact physical sizes,h ighly localized coherent output, and efficient wave-guiding. [1b, 2] Forp ractical use, development of NW laser arrays is of great importance for full-color laser displays,l aser lighting, and sensing applications. [3] Nevertheless,monolithic growth and patterning of III-Vs emiconductor NWs onto an arbitrary substrate remains af ormidable task, owing to material lattice mismatch and incompatible growth temperature. [4] Organic-inorganic halide hybrid perovskite materials are an emerging class of solution-processed semiconductors for high-efficiencyoptoelectronic devices, [5] which are promising for solar cells(SCs), [5b] light-emitting diodes (LEDs), [6] optical amplifiers, [7] and optically pumped lasers. [2,8] Recently,3 D perovskite nanowire (NW) lasers were demonstrated with low lasing thresholds and high quality factors. [2] On the one hand, these self-assembly NWs were solution grown with random orientation by exposing al ead acetate film to as olution of MA halide salt. [2] On the other hand, the instability owing to atmospheric moisture and halide ion migration is another challenge in 3D perovskite technology. [9] Tw o-dimensional (2D) organic-inorganic hybrid Ruddlesden-Popper perovskites (RPPs) are solution-processed quantum well (QW) materials [10] that show unique and promising advantages as compared with their 3D counterparts, [11] including both technologically relevant photo-/chemical stability and quantum tunable optoelectronic properties. [12] 2D RPPs adopt ac hemical formula as A' 2 A nÀ1 M n X 3n+1 with A' ao rganic cation larger than A. Thep erovskite framework [A nÀ1 M n X 3n+1 ] 2À layers are sandwiched between two organic layers composed of A' cations. [13] Dielectric constants difference between RPP and organic layers leads to effective confinement of electron-hole pairs within the [A nÀ1 M n X 3n+1 ] 2À layer, therefore inducing excitons th...

Optical resonator arrays are highly important fundamental units for integrated photoelectric devices, such as on‐chip logical circuits, high‐precision sensors, and laser displays. Whispering gallery mode (WGM) microrings (MRs) could reduce the optical losses and provide a small mode volume, which is helpful for the integration of miniaturized devices. However, there still is a great challenge to produce and pattern the circular resonator. Here, a facile poly(dimethylsiloxane) (PDMS) ring‐hole‐stamp confined solution‐growth method is used to fabricate organic (E)‐3‐(4‐(di‐p‐tolylamino)phenyl)‐1‐(1‐hydroxynaphthalen‐2‐yl)prop‐2‐en‐1‐one (DPHP) MR arrays. Low‐threshold multi‐mode near‐infrared lasing is successfully achieved in the single MRs and DPHP MR arrays at room temperature. At the same time, their lasing behaviors change obviously in the lasing intensity, emission position, lasing mode, and lasing threshold after contacting with water and NaOH solution. The present work is a major step for realizing compact near‐infrared optoelectronic devices.