Here, we design and synthesize an organic laser molecule, 2,7-diphenyl-9H-fluorene (LD-1), which has state-of-the-art integrated optoelectronic properties with a high mobility of 0.25 cm2 V–1 s–1, a high photoluminescence quantum yield of 60.3%, and superior deep-blue laser characteristics (low threshold of P th = 71 μJ cm–2 and P th = 53 μJ cm–2 and high quality factor (Q) of ∼3100 and ∼2700 at emission peaks of 390 and 410 nm, respectively). Organic light-emitting transistors based on LD-1 are for the first time demonstrated with obvious electroluminescent emission and gate tunable features. This work opens the door for a new class of organic semiconductor laser molecules and is critical for deep-blue optical and laser applications.

commonly used multicomponent strategy for white-light emitter, SMWLEs possess many attractive and distinctive advantages, such as absent phase separation, minimal color-aging, easy fabrication, good stability, etc. [2] However, the high-efficiency SMWLE has been always a serious scarcity, as a result of the extremely challenging single-molecule mechanism for whitelight emission according to the Kasha's rule. [3] Typically, the simultaneous dual emission or ternary emission is required to make up white-light emission in singlecomponent material, corresponding to two-color (blue and yellow/orange) or three-color (blue, green and red) emissive sources. [4] In terms of the simplest dual-emission strategy, it can be assigned to two emissive excited states: one excited state is responsible for blue emission and the other one contributes to yellow/orange emission. Usually, the former is locally excited (LE) singlet state, while the latter can be the one among charge-transfer (CT) state, [5] excimer state, [6] proton-transfer state, [7] self-assembly state, [8] the lowest triplet (T 1 ) excited state for room-temperature phosphorescence (RTP), [9] and so on. [10] What is more, this dual emission can also be assigned to dual RTP emission, corresponding to the coemission from both T 1 and T 2 states, respectively. [11] With the recent progress of pure organic RTP materials, [12] more and more dual emission of fluorescence and phosphorescence were observed with SMWLE property. However, the efficiency improvement of pure organic SMWLEs from the dual emission of fluorescence and phosphorescence is one of the most challenging issues. This is because that spin-orbit coupling (SOC) in pure organic systems is weak, which can afford neither the effective intersystem crossing (ISC) for triplet exciton generation nor the efficient triplet exciton radiation to surpass all possible nonradiations (e.g., vibrational quenching, oxygen quenching). [13] More importantly, in comparison with multicomponent white-light emitter, the difficulty will be dramatically increased to achieve the simultaneous enhancement of dual emission of fluorescence and phosphorescence. As for the reasons, there are many internal and external factors affecting these two emissive excited states (fluorescence and phosphorescence) and the balance between them due to the Developing the single-molecule white-light emitters (SMWLEs) at room temperature is very challenging for pure organic metal-free system, and it is even more challenging to achieve the high efficiency of pure organic SMWLE. Here, alkoxy substituents are tailored at 2-positioned thioxanthone (TX) to finely tune the molecular packing mode and the intermolecular interaction between TX units, and the photoluminescence (PL) efficiency (Φ PL ) of SMWLE is improved successfully from 1.5% (TX) to 45.0% (TX-OCH(CH 3 ) 2 ). This simultaneous enhancement of dual emission between fluorescence and phosphorescence can be ascribed to i) a moderate intersystem crossing (ISC) rate for the equilibrium distribution b...

Multimetallic nanostructures can be synthesized by integrating up to seven or eight metallic elements into a single nanoparticle, which represent a great advance in developing complex multicomponent nanoparticle libraries. Contrary, organic micro- and nanoparticles beyond three π-conjugated components have not been explored because of the diversity and structural complexity of molecular assemblies. Here, we report a library of microparticles composed of an arbitrary combination of four luminescent organic semiconductors. We demonstrate that the composition and emission color of each domain as well as its spatial distribution can be rationally modulated. Unary, binary, ternary, and quaternary microparticles are thus realized in a predictable manner based on the miscibility of the components, resulting in mixed-composition phases or alloyed or phase separated heterostructures. This work reports a simple yet available synthetic methodology for rational modulation of organic multicomponent microparticles with complex architectures, which can be used to direct the design of functional microparticles.

The spatial separation between the highest occupied and the lowest unoccupied molecular orbitals (HOMO and LUMO) in thermally activated delayed fluorescent (TADF) molecules leads to charge transfer (CT) states, which degrade the oscillator strength of emission transition and sacrifices high solid-state photoluminescence quantum yield (PLQY), together limiting its application in organic solid-state lasers (OSSLs). Here, we demonstrated organic microwire lasers from TADF emitters that combine aggregation induced emission (AIE) and local excited (LE) state characteristics. The unique AIE and LE feature lead to a PLQY approaching 50 % and a high optical gain of 870 cm À 1 for TADF microwires. The regenerated singlet excitons by reverse intersystem crossing (RISC) process are conducive to population inversion. As a result, we demonstrated microwire lasers around 465 nm with a low threshold of 3.74 μJ cm À 2 . Therefore, our work provides insight to design TADF materials for OSSLs.

The development of high mobility organic laser semiconductors with strong emission is of great scientific and technical importance, but challenging. Herein, we present a high mobility organic laser semiconductor, 2,7‐diphenyl‐9H‐fluorene (LD‐1) showing unique crystallization‐enhanced emission guided by elaborately modulating its crystal growth process. The obtained one‐dimensional nanowires of LD‐1 show outstanding integrated properties including: high absolute photoluminescence quantum yield (PLQY) approaching 80 %, high charge carrier mobility of 0.08 cm2 V−1 s−1, Fabry‐Perot lasing characters with a low threshold of 86 μJ cm−2 and a high‐quality factor of ≈2400. Furthermore, electrically induced emission was obtained from an individual LD‐1 crystal nanowire‐based light‐emitting transistor due to the recombination of holes and electrons simultaneously injected into the nanowire, which provides a good platform for the study of electrically pumped organic lasers and other related ultrasmall integrated electrical‐driven photonic devices.