Combining blue micro‐light‐emitting diodes (LEDs) with color conversion layers (CCLs) is a promising approach to develop efficient full‐color displays. However, no such practical display is reported so far potentially because of two major challenges, i.e., rarely available color conversion materials and severe crosstalk effect among adjacent pixels due to the thick sapphire substrates of LED chips. Here, a full‐color micro‐LED display prototype by combining rationally designed blue micro‐LEDs backlight with CsPbBr3 perovskite and CdSe QDs as green and red CCLs, respectively, is presented. The color gamut of the fabricated display can reach as high as 129% of the National Television Standards Committee (NTSC). Notably, the color gamut can still reach 126% NTSC even when only green light is converted through perovskite CCL while the other two colors are achieved from conventional micro‐LEDs. This is the first demonstration on employing perovskite materials as CCL in full‐color micro‐LEDs display.
Combined floating offshore wind platform and wave energy converter (WECs) systems have the potential to provide a cost-effective solution to offshore power supply and platform protection. The objective of this paper is to optimize the size and layout of WECs within the hybrid system under a given sea state with a numerical study. The numerical model was developed based on potential flow theory with viscous correction in the frequency domain to investigate the hydrodynamic performance of a hybrid system consisting of a floating platform and multiple heaving WECs. A non-dimensional method was presented to determine a series of variables, including radius, draft, and layout of the cylindrical WEC at a typical wave frequency as the initial design. WECs with larger diameter to draft ratio were found to experience relatively smaller viscous effects, and achieve more wave power, larger effective frequency range and similar wave power per unit volume in the same sea state. The addition of WECs reduced the maximum horizontal force and pitch moment on the platform, whereas the maximum vertical force increased due to the increasing power take-off force, especially at low frequencies. The results presented in this paper provide guidance for the optimized design of WECs and indicate the potential for synergies between wave and wind energy utilization on floating platforms.
The high power generation cost impedes commercial-scale wave power operations. The main objective of this work was to provide a cost-sharing solution through combing the wave extraction and costal protection performance. A two-dimensional numerical wave tank was developed using Star-CCM+ Computational Fluid Dynamics software to investigate the hydrodynamic performance of a dual floater hybrid system consisting of a floating breakwater and an oscillating-buoy type wave energy converter (WEC). The new model was verified with published experimental results. The differences between the hydrodynamic performance of the hybrid system, a single WEC and a single breakwater were compared. The effects of the wave resonance in the WEC-breakwater gap and the geometrical parameters on the performance of the asymmetric WEC were also studied. It was found that the hybrid system demonstrated both better wave attenuation and wave energy extraction capabilities at low wave frequencies, i.e., wider effective frequency. The forces on the breakwater were generally reduced due to the WEC. Wave resonance in the narrow gap has an adverse effect on the hybrid system with an asymmetric WEC, while a beneficial effect with a symmetric WEC. The wave energy conversion efficiency of hybrid system can be improved by increasing the draft and width of the WEC and decreasing the distance between the WEC and the breakwater. The findings of this paper make wave energy economically competitive and commercial-scale wave power operations possible.
Phosphor with extremely narrow emission line widths, high brightness, and wide color emission tunability in visible regions is required for display and lighting applications, yet none has been reported in the literature so far. In the present study, single-sized lead halide perovskite (APbX 3; A = CH3NH3 and Cs; X = Cl, Br, and I) nanocrystalline (NC) phosphors were achieved for the first time in a one-pot reaction at room temperature (25 °C). The size-dependent samples, which included four families of CsPbBr3 NCs and exhibited sharp excitonic absorption peaks and pure band gap emission, were directly obtained by simply varying the concentration of ligands. The continuity of the optical spectrum can be successively tuned over the entire UV-visible spectral region (360-610 nm) by preparing CsPbCl3, CsPbI3, and CsPb(Y/Br)3 (Y = Cl and I) NCs with the use of CsPbBr3 NCs as templates by anion exchange while maintaining the size of NCs and high quantum yields of up to 80%. Notably, an emission line width of 10-24 nm, which is completely consistent with that of their single particles, indicates the formation of single-sized NCs. The versatility of the synthetic strategy was validated by extending it to the synthesis of single-sized CH3NH3PbX 3 NCs by simply replacing the cesium precursor by the CH3NH3 X precursor.
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