In this paper, we report two new phenanthroline-based compounds, 1,4-bis­(2-phenyl-1,10-phenanthrolin-4-yl)­benzene (p-bPPhenB) and 1,3-bis­(2-phenyl-1,10-phenanthrolin-4-yl)­benzene (m-bPPhenB), for the charge generation unit of tandem organic light-emitting diodes (OLEDs). These two compounds exhibited high electron mobility of (5.8–4.4) × 10–3 cm2/(V s), a very small injection barrier at the p–n junction interface, a high glass transition temperature of 123.9–182.1 °C, and exceptionally good operational stability. Because of such excellent characteristics, a single-stack red phosphorescent OLED (PhOLED) with p-bPPhenB showed a low driving voltage (2.7 V) and significantly improved maximum power efficiency (56.8 lm/W), external quantum efficiency (30.8%), and device lifetime (LT95, 130 h) compared to those of the control device using bathophenanthroline (Bphen) (3.7 V, 39 lm/W, 27.1%, and 13 h). Furthermore, a two-stack (tandem) red PhOLED using p-bPPhenB in the charge generation unit exhibited superior charge generation as well as electron transport properties and excellent device performances (5.0 V, 54.0 lm/W, 56.1%) compared to those of the tandem device using Bphen (6.2 V, 45.2 lm/W, 53.3%).

Two new hole-extraction materials, TPDI (5,10,15-triphenyl-5H-diindolo[3,2-a:3 0 ,2 0 -c]carbazole) and TBDI (5,10,15-tribenzyl-5H-diindolo[3,2-a:3 0 ,2 0 -c]carbazole), were synthesized and explored in planar heterojunction organic solar cells (OSCs). The synthesized materials have good transparency in the visible spectrum, high hole mobility, and compatible highest occupied molecular orbital (HOMO) values with the donor material, which make them excellent hole-extraction layers (HELs) for OSCs. The SubPc (subphthalocyanine chloride)/C 60 and SubNc (subnaphthalocyanine chloride)/C 60 OSCs with a TBDI HEL show impressive 35.9% and 29.1% improvements in power conversion efficiencies compared to reference devices. Their HOMO values were evaluated as 5.2-5.3 eV and hole mobilities were measured as 5.9-6.1 Â 10 À3 cm 2 V À1 s À1 at 0.3 MV cm À1 by the space-charge limited current method.

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Transparent organic light emitting diodes (TOLED) have widespread applications in the next-generation display devices particularly in the large size transparent window and interactive displays. Herein, we report high performance and stable attractive smart window displays using facile process. Advanced smart window display is realized by integrating the high performance light blocking screen and highly transparent white OLED panel. The full smart window display reveals a maximum transmittance as high as 64.2% at the wavelength of 600 nm and extremely good along with tunable ambient contrast ratio (171.94:1) compared to that of normal TOLED (4.54:1). Furthermore, the performance decisive light blocking screen has demonstrated an excellent optical and electrical characteristics such as i) high transmittance (85.56% at 562nm) at light-penetrating state, ii) superior absorbance (2.30 at 562nm) in light interrupting mode, iii) high optical contrast (85.50 at 562 nm), iv) high optical stability for more than 25,000 cycle of driving, v) fast switching time of 1.9 sec, and vi) low driving voltage of 1.7 V. The experimental results of smart window display are also validated using optical simulation. The proposed smart window display technology allows us to adjust the intensity of daylight entering the system quickly and conveniently.