The aggregation-induced emission (AIE) phenomenon is important in organic light-emitting diodes (OLEDs), for it can potentially solve the aggregationcaused quenching problem. However, the performance of AIE fl uorophorbased OLEDs (AIE OLEDs) is unsatisfactory, particularly for deep-blue devices (CIEy < 0.15). Here, by enhancing the device engineering, a deep-blue AIE OLED exhibits low voltage (i.e., 2.75 V at 1 cd m −2 ), high luminance (17 721 cd m −2 ), high effi ciency (4.3 lm W −1 ), and low effi ciency roll-off (3.6 lm W −1 at 1000 cd m −2 ), which is the best deep-blue AIE OLED. Then, blue AIE fl uorophors, for the fi rst time, have been demonstrated to achieve high-performance hybrid white OLEDs (WOLEDs). The two-color WOLEDs exhibit i) stable colors and the highest effi ciency among pure-white hybrid WOLEDs (32.0 lm W −1 ); ii) stable colors, high effi ciency, and very low effi ciency roll-off; or iii) unprecedented effi ciencies at high luminances (i.e., 70.2 cd A −1 , 43.4 lm W −1 at 10 000 cd m −2 ). Moreover, a three-color WOLED exhibits wide correlated color temperatures (10 690-2328 K), which is the fi rst hybrid WOLED showing sunlight-style emission. These fi ndings will open a novel concept that blue AIE fl uorophors are promising candidates to develop high-performance hybrid WOLEDs, which have a bright prospect for the future displays and lightings.

Flexible WOLEDs with extremely high efficiency and color-stability are realizedviathe extraordinary combination of mechanical, electrical and optical properties.

Currently, high efficiency, low efficiency roll-off and stable color white organic lightemitting diodes (WOLEDs) are still challenging to realize via simplified structures. Herein, the simplicity/ extremely high efficiency/ low efficiency roll-off/ stable color trade-off has been accomplished in a single-emitting-layer (single-EML) phosphorescent WOLED. The WOLED exhibits total efficiencies of 111.7 cd A -1 and 75.5 lm W -1 at the practical luminance of 1000 cd m -2 , which are the highest among single-EML WOLEDs. Even at 5000 cd m -2 , the efficiencies are remained as high as 101.3 cd A -1 and 58.8 lm W -1 . Besides, the color variation in the whole range of luminances is (0.00, 0.00), which is the first single-EML WOLED with an extremely stable color. The origin of the high performance is unveiled. Particularly, the role of guests, which is often ignored in single-EML WOLEDs, on the origin of color-stability is systematically revealed and the harnessment of charges and excitons distribution by using multifunctional guests is demonstrated to be critical to stabilizing the color. Such marvelous results not only represent a significant step towards the realization of simplified WOLEDs, but also provide a new opportunity to achieve extremely stable colors [ΔCIE (Commission International de I'Eclairage)= (0.00, 0.00)].