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Herein, we demonstrated a steric-hindrance-controlled laser switch in pure metal-organic framework (MOF) microcrystals. The well-faceted MOF microwires with aggregation-induced emission (AIE) lumnogens as linkers function as typical Fabry-Pérot microlasers. The steric hindrance around the AIE linkers can be reduced by the loss of guest molecules, which lead to the enhanced rotation of linkers with red-shifted gain behavior. On this basis, the gain region was readily switched through changing the steric hindrance via the desorption/adsorption of guests. As a result, the reversible switching of the dual-wavelength lasing from MOF microwires was achieved. The results provide a promising route to the development of versatile micro-/nanolasers with desired applications.

Multicomponent crystallization is universally important in various research fields including materials science as well as biology and geology, and presents new opportunities in crystal engineering. This process includes multiple kinetic and thermodynamic events that compete with each other, wherein "external triggers" often help the system select appropriate pathways for constructing desired structures. Here we report an unprecedented finding that a lattice strain accumulated with the growth of a crystal serves as an "internal trigger" for pathway selection in multicomponent crystallization. We discovered a "spontaneous" crystal transition, where the kinetically preferred layered crystal, initially formed by excluding the pillar component, carries a single dislocation at its geometrical center. This crystal "spontaneously" liberates a core region to relieve the accumulated lattice strain around the dislocation. Consequently, the liberated part becomes dynamic and enables the pillar ligand to invade the crystalline lattice, thereby transforming into a thermodynamically preferred pillared-layer crystal.

[K(dibenzo-18-crown-6)]+ (KC) cations are used for cocrystallization with manganese halides, producing isostructural single crystals of organic–inorganic hybrid complexes, [K(dibenzo-18-crown-6)]2M...

In this work, we demonstrate a stimulated emission-controlled photonic transistor on a single organic triblock nanowire composed of alternate energy donor and acceptor. The population of acceptor excitons was engineered by energy transfer to achieve enhanced fluorescence, which was further amplified by the stimulated emission of the donor and the optical feedback in the nanowire microcavities, yielding a remarkable nonlinear amplification of the acceptor emission. On this basis, a prototype of photonic transistor with high nonlinear gain at very low pump energy was achieved. The results will provide a useful enlightenment for the rational design of novel all-optical switches with desired performances.

All-color subwavelength output of lasers was demonstrated in a rationally designed organic microdisk/silver nanowire heterostructures. The dye-doped flexible microdisks served as the wavelength tunable whispering-gallery-mode lasers with low lasing thresholds, whereas the silver nanowires supported the output of the lasing mode as subwavelength coherent light sources. The wavelength of the outcoupled laser was tuned over the full visible spectrum scope owing to the flexibility of the microdisks and their compatibility with various organic laser dyes. Furthermore, a multicolor subwavelength laser was achieved in a single heterostructure and the laser output was successfully modulated by varying the surface plasmon polariton propagation length.

Polymorphism and anisotropy are fundamental phenomena of crystalline materials. However, the structure-dependent photoluminescent (PL) anisotropy in polymorphic organic crystals has remained unexplored. Herein, two polymorphic nanocrystals, green-emitting nanorods (PtD-g) and yellow-emitting nanoplates (PtD-y), were obtained from a platinum(II)−β-diketonate complex. The PtD-y crystals display remarkable PL anisotropy with an anisotropy ratio of up to 0.87 whereas the emission of the PtD-g crystals is nearly unpolarized. The polarization properties are rationalized on the different molecular packing of these crystals. By light-harvesting energy transfer, the PtD-y crystals are successfully used to amplify the emission polarization of a red-emitting platinum acceptor (PtA) doped into the donor crystalline matrix, which is otherwise weakly polarized as pure crystals.

We propose a general approach for obtaining dual-wavelength organic microlasers in amphiphilic Janus resonators, where hydrophilic and hydrophobic dyes can be spatially separated via polarity-driven encapsulation. Low-threshold dual-wavelength lasing was achieved in a single Janus particle with well-modulated output. This universal approach enables flexibly designing the lasing wavelength of the Janus microlasers in the full visible spectrum by systematically altering the encapsulated laser dyes. Our findings demonstrate a promising route to the photonic integration at the micro-/nanoscale that may lead to the innovation of concepts and device architectures for multifunctional optoelectronic applications.

Nanoscale lasers are ideal light-signal sources for integrated photonic devices. Most of the present lasers made of dielectric materials are restricted to being larger than half the wavelength of the optical field. Plasmon lasers made from metallic nanostructures can help to break the diffraction limit, yet they suffer from low optical pump efficiencies and low quality factors. Integrating dielectric lasers with plasmonic waveguides to construct hybrid material systems may circumvent these problems and combine the advantages of the two components. Here we demonstrate the nanoscale output of dielectric lasers via photon-plasmon coupling in rationally designed perovskite/silver heterostructures. The perovskite crystals offer the gain and high-Q cavity for low-threshold laser generation, while the embedded silver nanowires (AgNWs) help to output the lasing modes efficiently in the form of surface plasmons. The output coupling can be modulated by controlling the resonant modes of the two-dimensional perovskite microcavities. The results would pave an alternative avenue to ultrasmall light sources as well as fundamental studies of light-matter interactions.

Wavelength tunable micro/nanolasers are indispensable components for various photonic devices. Here, we report broadband tunable microlasers built by incorporating a highly polarized organic intramolecular charge-transfer (ICT) compound with a supramolecular host. The spatial confinement of the ICT dye generates an optimized energy level system that favors controlled population distribution between the locally excited (LE) state and the twisted intramolecular charge-transfer (TICT) state, which is beneficial for significantly broadening the tailorable gain region. As a result, we realized a wide tuning of lasing wavelength in the organic supramolecular microcrystals based on temperature-controlled population transfer from the LE to TICT state. The results will provide a useful enlightenment for the rational design of miniaturized lasers with desired performances.

Real-time visualization of assembly processes and sophisticated signal processing at the nanoscale are two challenging topics in photonic nanomaterials. Here, high-quality light-harvesting crystalline nanorods were developed by the coassembly of two polypyridyl Ir(III) and Ru(II) metallophosphors, behaving as the antenna chromophore and energy acceptor, respectively. By using a one-pot or stepwise growth condition, homogeneous and multiblock heterojunction nanorods were prepared, respectively. These nanostructures display multicolor phosphorescence from green to red due to the efficient triplet energy transfer and light-harvesting capability at low acceptor doping ratios. Heterojunction nanorods show gradient emission-color switches during different growth stages, in which the real-time stepwise assembly can be vividly visualized using fluorescence microscopy techniques. Triplet excitons were successfully manipulated in both homogeneous and heterojunction nanorods to realize waveguided green, orange, and red emissions and advanced photonic signal logics and encoding/decoding on single multiblock heterojunction nanorod.

Flexible microdisk whispering-gallery-mode (WGM) resonators with high quality factors were achieved through the controlled assembly of organic materials with an emulsion-solvent-evaporation method. The high material compatibility of the assembled microdisks enabled us to realize low-threshold WGM lasers by doping with organic dyes as gain media. Furthermore, the emulsion-assisted self-assembly provided a strategy for the one-step fabrication of microwire-waveguide-connected microdisk heterostructures, which can be utilized for the efficient output of the isotropic WGM lasers from the coupled waveguides. We hope that these results will pave an avenue for the construction of new types of flexible WGM-based components for photonic integration.

Single-crystal organic nanowires were fabricated with a soft-template-assisted self-assembly method in liquid phase. These nanowires with rectangular cross section can serve as resonators for exciton-photon coupling, leading to a microcavity effect and a relatively low threshold of laser actions. Two-photon-pumped blue lasing was observed in these organic waveguiding nanostructures above a threshold of 60 nJ, excited with a 750 nm near-infrared femtosecond pulse laser at 77 K.

Vertical organic nanowire arrays of 1,5-diaminoanthraquinone (DAAQ) on solid substrates were prepared by a facile physical vapor transport method. The crystal structure and growth direction of the nanowires were determined with electron diffraction. The color and fluorescence of the DAAQ nanowires can be bleached and quenched by acid vapor and rapidly regenerated by base vapor, making them useful as optical sensor materials. The ease of oriented vertical growth makes them promising nanophotonic elements that may be directly integrated into photonic devices during growth.