The ultraviolet random lasing behavior of an ensemble of ZnO nanocombs has been demonstrated. It is found that the Fabry-Perot resonance induced by nanocomb geometry can greatly enhance random lasing action with a low threshold condition. Besides, the emission spectra exhibit few sharp lasing peaks with a full width at half maximum (FWHM) of less than 0.3 nm and a narrow background emission with a FWHM of about 5 nm. Cathodoluminescence mapping images are utilized to analyze the Fabry-Perot resonance phenomenon. The resonant effect on the lasing system is further confirmed by nanocombs with different resonant cavity lengths. The unique lasing behavior induced by the simultaneous occurrence of Fabry-Perot resonance and random laser action shown here may open up a new possibility for the creation of highly efficient light emitting devices.

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A new and general approach to enhance band-edge emission at the expense of defect emission in a semiconductor nanocomposite is proposed. The underlying mechanism is based on the resonance effect between defect transition and band-to-band excitation and transfer of excited electrons between conduction band edges. With our approach, it is possible to convert defect loss into bandgap emission. As an example, we demonstrate that the bandgap emission of ZnO nanorods can be enhanced by as much as 30 times when they are compounded with CdSe/ZnS nanoparticles.

During the last two decades, spectacular development of light-emitting diodes (LEDs) has been achieved owing to their widespread application possibilities. However, traditional LEDs suffer from unavoidable energy loss because of the down conversion of photons, toxicity due to the involvement of rare-earth materials in their production, higher manufacturing cost, and reduced thermal stability that prevent them from all-inclusive applications. To address the existing challenges associated with current commercially available white LEDs, herein, we report a broad-band emission originating from an intrinsic lanthanide-free single-molecule-based LED. Self-assembly of a butterflyshaped strontium-based compound {[Sr(H 2 btc) 2 (MeOH)(H 2 O) 2 ]• 2H 2 O} (1) was achieved through the reaction of Sr(NO 3 ) 2 with 1,2,3benzenetricarboxylic acid hydrate (1,2,3-H 3 btc) under hydrothermal conditions. A white LED based on this single molecule exhibited a remarkable broad-band luminescence spectrum with Commission Internationale de l'Eclairage (CIE) coordinates at (0.33, 0.32) under 30 mA current injection. Such a broad luminescence spectrum can be attributed to the simultaneous existence of several emission lines originating from the intramolecular interactions within the structure. To further examine the nature of the observed transitions, density functional theory (DFT) calculations were carried out to explore the geometric and electronic properties of the complex. Our study thus paves the way toward a key step for developing a basic understanding and the development of high performance broad-band light-emitting devices with environment-friendly characteristics based on organic−inorganic supramolecular materials.

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