Context: Among the challenges being faced to improve the efficiency of LED-based white light sources is the development of more efficient phosphors. As of 2010, the most efficient yellow phosphor is still the YAG phosphor, with less than 10% Stoke shift loss. Losses attributable to internal optical losses due to re-absorption in the LED chip and in the LED packaging itself account typically for another 10% to 30% of efficiency loss. Currently, in the area of phosphor LED development, much effort is being spent on optimizing these devices to higher light output and higher operation temperatures. For instance, the efficiency can be raised by adapting better package design or by using a more suitable type of phosphor. Conformal coating process is frequently used to address the issue of varying phosphor thickness.

Question: What can improve the efficiency of LED-based white light?
Answer: more efficient phosphors

Question: What is the most efficient yellow phosphor?
Answer: YAG phosphor

Question: What is the percentage of stoke shift loss in YAG phosphor?
Answer: less than 10%

Question: What area are scientists looking into regarding phosphor LED development?
Answer: higher operation temperatures

Question: What is one method that can raise the efficiency of phosphor-based LEDs?
Answer: adapting better package design

Question: What can improve the efficiency of non-LED-based white light?
Answer: Unanswerable

Question:  What is the least efficient yellow phosphor?
Answer: Unanswerable

Question:  What is the percentage of stoke shift loss in non-YAG phosphor?
Answer: Unanswerable

Question: What area are scientists looking into regarding phosphor non-LED development?
Answer: Unanswerable

Question: What is one method that can lower the efficiency of phosphor-based LEDs?
Answer: Unanswerable