The authors would like to gratefully acknowledge research grants from National Natural Science Foundation of China (Grant No. 21706060, 51703061), Natural Sciences Foundation of Hunan Province, China (Grant No. 2016JJ3065, 2017JJ3103), National Science Foundation for Postdoctoral Scientists of China (Grant No. 2016M592427). The authors also like to thank Dequan Liu, Ronghua Wang and Huazhu Song from Pursuit LED lighting company for the help of the devices fabrication. The authors would like to thank Elsevier (webshop.else-vier.com) for the English language review.