3,371 research outputs found
Structural and spectral dynamics of single-crystalline Ruddlesden-Popper phase halide perovskite blue light-emitting diodes.
Achieving perovskite-based high-color purity blue-emitting light-emitting diodes (LEDs) is still challenging. Here, we report successful synthesis of a series of blue-emissive two-dimensional Ruddlesden-Popper phase single crystals and their high-color purity blue-emitting LED demonstrations. Although this approach successfully achieves a series of bandgap emissions based on the different layer thicknesses, it still suffers from a conventional temperature-induced device degradation mechanism during high-voltage operations. To understand the underlying mechanism, we further elucidate temperature-induced device degradation by investigating the crystal structural and spectral evolution dynamics via in situ temperature-dependent single-crystal x-ray diffraction, photoluminescence (PL) characterization, and density functional theory calculation. The PL peak becomes asymmetrically broadened with a marked intensity decay, as temperature increases owing to [PbBr6]4- octahedra tilting and the organic chain disordering, which results in bandgap decrease. This study indicates that careful heat management under LED operation is a key factor to maintain the sharp and intense emission
Recent progress of coherent beam combining Kumgang Laser (0.4J@10kHz/10ns)
A coherent beam combining is the most
promising technique to achieve a high output energy
and a high repetition rate laser system with
a good beam quality [1]. It has been demonstrated
experimentally that the coherent beam
combination using self-phase-controlled stimulated
Brillouin scattering phase conjugate mirror
(SC-SBS-PCM) is the simplest coherent beam
combination method [2-3].
For an average output power of a kW range, the
experimental verification of coherent beam combination
is now underway by the Kumgang laser
[4-5]..
Recent progress of coherent beam combining Kumgang Laser (0.4J@10kHz/10ns)
A coherent beam combining is the most
promising technique to achieve a high output energy
and a high repetition rate laser system with
a good beam quality [1]. It has been demonstrated
experimentally that the coherent beam
combination using self-phase-controlled stimulated
Brillouin scattering phase conjugate mirror
(SC-SBS-PCM) is the simplest coherent beam
combination method [2-3].
For an average output power of a kW range, the
experimental verification of coherent beam combination
is now underway by the Kumgang laser
[4-5]..
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