Fluorescent‐based tandem white OLEDs designed for display and solid‐state‐lighting applications

Abstract

Abstract— Highly efficient tandem white OLEDs based on fluorescent materials were developed for display and solid‐state‐lighting (SSL) applications. In both cases, the white OLED must have high power efficiency and long lifetime, but there are a number of attributes unique to each application that also must be considered. Tandem OLED technology has been demonstrated as an effective approach to increase luminance, extend OLED lifetime, and allow for use of different emitters in the individual stacks for tuning the emission spectrum to achieve desired performance. Here, examples of bottom‐emission tandem white OLEDs based on small‐molecule fluorescent emitters designed for displays and for SSL applications are reported. A two‐stack tandem white OLED designed for display applications achieved 36.5‐cd/A luminance efficiency, 8500K color temperature, and lifetime estimated to exceed 50,000 hours at 1000 cd/m2. This performance is expected to meet the specifications for large AMOLED displays. A two‐stack tandem white OLED designed for SSL applications achieved 20‐lm/W power efficiency, 38‐cd/A luminance efficiency, 3500K color temperature, and lifetime estimated to exceed 140,000 hours at 1000 cd/m2. With the use of proven light‐extraction techniques, it is estimated that this tandem device will exceed 40 lm/W with more than 500,000‐hour lifetime, performance that should be sufficient for first‐generation lighting products.

Highly Efficient Hybrid White Tandem Organic Light‐Emitting Diodes with MoO3 Layer

“…One uses two identical white color emitting EL unit, [2,4,5] the other uses different color (complementary color such as blue and yellow) emitting EL units. [6][7][8] The former is called symmetric tandem OLEDs, while the latter is called asymmetric tandem OLEDs. Maximum current efficiency of 23.9 cd/A, power efficiency of 7.8 lm/W, and EQE of 8.5% have been obtained from symmetric tandem white OLED with two identical fluorescence EL units.…”

Organic semiconductor heterojunctions as charge generation layers and their application in tandem organic light-emitting diodes for high power efficiency

“…Combined with the high efficiency and long lifetime, tandem white OLEDs have great potential in the fields of display and solid-state lighting. 8,10,12,15,[42][43][44][45][46] …”

“…109,110 Today's state-of-the-art tandem WOLEDs that vertically stack either individual red, green, and blue emission units or multiple white emission units in series via CGLs may be an effective approach to obtain white light since the efficiency and luminance can be doubled and better stability can be achieved. 8,10,12,15,[42][43][44][45][46] However, the tandem WOLEDs based on conventional CGLs cannot exhibit the enhancement of power efficiency with respect to the single-unit devices due to the high operational voltage. As demonstrated above, using OHJs as CGLs can enhance the power efficiency of the fabricated tandem OLEDs.…”

“…As demonstrated above, using OHJs as CGLs can enhance the power efficiency of the fabricated tandem OLEDs. Accordingly, we fabricated tandem WOELDs based on OHJs as CGLs, and found that the power efficiency of the tandem WOLEDs we made is indeed enhanced and the efficiency roll-off is greatly reduced compared to the conventional CGLbased tandem WOLEDs 8,10,12,15,[42][43][44][45][46] Fig. 14 shows the device structures of the tandem WOLEDs based on conventional TPBi:Li 2 CO 3 /TCTA:MoO 3 CGLs (Fig.…”

52.2: Hybrid Tandem White OLEDs with High Efficiency and Long Life‐time for AMOLED Displays and Solid‐State Lighting

“…Efficiency, lifetime, and white color are key considerations for such applications. Tandem OLED structures have enabled improved lifetime, power efficiency, and easy adjustment of color both for displays and lighting applications [1][2][3][4] . Hybrid tandems that combine fluorescent blue and phosphorescent green and red (or orange) have shown much higher efficiency than those tandems based on all-fluorescent materials [5][6][7] .…”