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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.

A polydimethylsiloxane cylindrical-hole-template-confined solution-growth method is developed to fabricate densely packed CsPbCl Br microdisk laser arrays. Furthermore, a strategy to integrate multicolored microdisk laser (MDL) arrays is demonstrated that simultaneously lase in the deep blue, blue, cyan, and green by means of gas-phase replacement of Cl by Br from initial CsPbCl MDLs in HBr vapor.

Zero-dimensional (0D) perovskite CsPbBr has been speculated to be an efficient solid-state emitter, exhibiting strong luminescense on achieving quantum confinement. Although several groups have reported strong green luminescence from CsPbBr powders and nanocrystals, doubts that the origin of luminescence comes from CsPbBr itself or CsPbBr impurities have been a point of controversy in recent investigations. Herein, we developed a facile one-step solution self-assembly method to synthesize pure zero-dimensional rhombohedral CsPbBr micro-disks (MDs) with a high PLQY of 52% ± 5% and photoluminescence full-width at half maximum (FWHM) of 16.8 nm. The obtained rhombohedral MDs were high quality single-crystalline as demonstrated by XRD and SAED patterns. We demonstrated that CsPbBr MDs and CsPbBr MDs were phase-separated from each other and the strong green emission comes from CsPbBr. Power and temperature dependence spectra evidenced that the observed strong green luminescence of pure CsPbBr MDs originated from direct exciton recombination in the isolated octahedra with a large binding energy of 303.9 meV. Significantly, isolated PbBr octahedra separated by a Cs ion insert in the crystal lattice is beneficial to maintaining the structural stability, depicting superior thermal and anion exchange stability. Our study provides an efficient approach to obtain high quality single-crystalline CsPbBr MDs with highly efficient luminescence and stability for further optoelectronic applications.

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.

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One-dimensional (1D) ribbon-like and two-dimensional (2D) square-like perylene crystals were prepared in a controlled manner via a simple drop-casting solution method by changing the temperature and concentration of the solution.

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...