We proposed a flexible and mask-less approach to directly fabricate a patterned red phosphor layer on a Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce 3+) phosphor-in-glass (PiG) for high-power white light-emitting diodes (WLEDs). This approach was realized by ultraviolet (UV) assisted and initiative cooling based water condensing. A low-temperature precursor glass matrix with a high refractive index was synthesized for the YAG:Ce 3+ PiG. By controlling the UV pre-curing time, the micro-concaves with adjustable sizes were fabricated on the red phosphor layer embedded with UV-curable polymer. With the pre-curing time of 20 s, 30 s, and 40 s, the average aspect ratio of the micro-concave is 1.03, 0.76, and 0.41, respectively. Consequently, the patterned sample achieves a highest luminous efficacy (LE) of 108.5 lm/W at the current of 350 mA, which is 16.2% higher than the unpatterned sample. The corresponding correlated color temperature (CCT) and color rendering index (CRI) are 4831 K and 80.5, respectively. The results demonstrate that the YAG:Ce 3+ PiG coated with the water condensing patterned red phosphor layer is a feasible and effective method to enhance the light extraction and color quality of high-power WLEDs.

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Microlens arrays (MLAs) have attracted wide attention due to their crucial applications in optics, optoelectronics, and biochemistry. In this paper, we present a simple and green approach for the economical fabrication of MLAs with controlled curvature based on water condensing. By controlling the input current and working time of initiative cooling and the viscoelasticity of UV-curable polymer, uniform porous films with adjustable morphology were prepared. MLAs with aspect ratios of 1.41, 1.01, and 0.69 were fabricated by micromolding the porous film templates. Furthermore, the fluoropolymer encapsulations with the MLAs were applied for the packaging of deep ultraviolet light-emitting diodes (DUV-LEDs). Consequently, the light output powers of DUV-LEDs are enhanced by 7.1%, 10.2%, and 15.4%, respectively, by using these MLAs at the driving current of 350 mA.

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