Color design model of high color rendering index white-light LED module.

The traditional white-light light-emitting diode (LED) is packaged with a single chip and a single phosphor but has a poor color rendering index (CRI). The next-generation package comprises two chips and a single phosphor, has a high CRI, and retains high luminous efficacy. This study employs two chips and two phosphors to improve the diode's color tunability with various proportions of two phosphors and various densities of phosphor in the silicone used.

Measurement of LED chips using a large-area silicon photodiode.

We propose the output power measurement of bare-wafer/chip light-emitting diodes (LEDs) using a large-area silicon (Si) photodiode with a simple structure and high accuracy relative to the conventional partial flux measurement using an integrating sphere. To obtain the optical characteristics of the LED chips measured using the two methods, three-dimensional ray-trace simulations are used to perform the measurement deviations owing to the chip position offset or tilt angle. The ray-tracing simulation results demonstrate that the deviation of light remaining in the integrating sphere is approximately 65% for the vertical LED chip and 53% for the flip-chip LED chip if the measurement distance in partial flux method is set to be 5-40 mm.

Curved remote phosphor structure for phosphor-converted white LEDs.

A phosphor-converted light emitting diode with curved remote phosphor layer was obtained in this study. By changing the geometry of the flat remote phosphor layer in a conventional remote phosphor structure, the package extraction efficiency and luminous efficacy of the curved remote phosphor structure was improved by reducing the total internal reflection at the interface of the air and phosphor layer. Ray tracing simulations were performed to analyze the package extraction efficiency of the curved remote phosphor structure.