We present a facile fabrication process to directly fabricate cone-shaped microwells arrays on single crystal Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce) ceramic phosphor platelets (CPPs) by short-pulse laser direct patterning. Compared to unpatterned YAG:Ce CPP with smooth surface, the forward-to-total ratio of emission photons of patterned YAG:Ce CPPs was enhanced from 53.2% up to 78.2%, and the total emission within 4-π degree is 6% higher. The fabricated patterns are also beneficial in increasing the color conversion efficiency of YAG:Ce CPPs by 7.6%. The patterned YAG:Ce CPPs display much better correlated color temperature (CCT) uniformity under varied currents. The angular correlated color temperature uniformity (ACU) of patterned YAG:Ce CPPs reaches as high as 0.933 compared to 0.730 of the unpatterned one. These results suggest that laser patterning of YAG:Ce CPP could effectively manipulate its luminance, chromaticity and illumination pattern, which may lead to further technological advancements for diversified applications of film-type CPPs in highly efficient white LEDs.

In this work, we have successfully fabricated microtubes by strain-induced self-rolling of a InGaN/GaN quantum wells nanomembrane. Freestanding quantum wells microtubes, with a diameter of 6 µm and wall thickness of 50 nm, are formed when the coherently strained InGaN/GaN quantum wells heterostructure is selectively released from the hosting substrate. Periodic oscillations due to whispering-gallery modes resonance were found superimposed on photoluminescence spectra even at low optical excitation power. With increasing pumping power density, the microtube is characterized by a stimulated emission with a threshold as low as 415 kW/cm². Such emission shows predominant TM polarization parallel to the microtube axis.

The size of the V-defects in the GaN/InGaN-based quantum wells blue light-emitting diode (LED) was intentionally modified from 50 nm to 300 nm. High resolution photoluminescence and electroluminescence of a single large V-defect were investigated by near-field scanning optical microscopy. The current distribution along the {10-11} facets of the large defect was measured by conductive atomic force microscopy. Nearly 20 times the current injection and dominant emission from bottom quantum wells were found in the V-defect compared to its vicinity. Such enhanced current injection into the bottom part of quantum wells through V-defect results in higher light output power. Reduced external quantum efficiency droops were achieved due to more uniform carrier distribution. The un-encapsulated fabricated chip shows light output power of 172.5 mW and 201.7 mW at 400 mA, and external quantum efficiency drop of 22.3% and 15.4% for the sample without and with large V-defects, respectively. Modified V-defects provide a simple and effective approach to suppress the efficiency droop problem that occurs at high current injection, while improving overall quantum efficiency.

Recent advances in the development of surface plasmons (SPs) enhanced LED have provided a great opportunity to enhance either the internal quantum efficiency (IQE) or the spontaneous emission rate (SE) by employing specific metal structures. However, it is still challenging to simultaneously achieve high IQE and Purcell factor (F_p), which demonstrates the SE enhancement, without sacrificing the electrical performance of LEDs. Herein, we designed and investigated a conic metal structure applied to LEDs by comprehensively considering the electrical, optical, and data transmission performance of devices. Conic structures with various heights were implemented to investigate the variation trends of IQE and F_p with the structure design, accompanied by the planar structures as references. A more than five times increase in IQE and almost five times increase in F_p were demonstrated experimentally even with a coupling distance of 100 nm, by employing this conic structure. The theoretical analysis was verified by the experimental results and revealed the mechanism of high F_p and IQE toward high SP–photon coupling efficiency and initial IQE. This study provides a universal strategy to enhance the performance of luminous efficiency and modulation speed of LEDs without sacrificing electrical properties, making them viable for the integration of lighting, display, and communication.