48‐2: Design Strategies of Fluorescent Dopants toward Pure Blue for Highly Efficient Top Emission OLEDs

Abstract

A blue dopant (BD) emitting pure blue fluorescence was created on new design strategies that combined specific partial molecular structures to reduce peak shoulder of the fluorescence spectrum. The top emission organic light emitting diode using the new BD achieved L/J/CIEy=201, which was about 10% higher than the conventional BD.

Realization of ultra‐high‐efficient fluorescent blue OLED

“…In SID 2020, we reported that the TE device with our BD material with narrow emission band shows high performance in terms of efficiency 18 . In this paper, the TE device of bilayer EML was fabricated using the narrow‐band BD and compared with that of the monolayer EML.…”

“…In SID 2020, we reported that the TE device with our BD material with narrow emission band shows high performance in terms of efficiency. 18 In this paper, the TE device of bilayer EML was fabricated using the narrowband BD and compared with that of the monolayer EML. As a result, the improvement effect on efficiency and lifetime was confirmed even in TE device, and blue index (BI) = 259 and LT95 = 198 h were achieved (Table 6 and Figure 9).…”

“…In the design of blue dopants (BDs), the orientation of BDs' transition dipole parallel to the substrates can improve the light extraction efficiency 12–15 . Furthermore, specializing in the light extraction efficiency of top emission (TE) devices, it was discussed from the viewpoint of the importance of the micro cavity structure and narrower emission spectral shape of BDs 16–18 . In this paper, we introduce a bilayer EML technology to realize the TTF efficiency maximization aiming at theoretical limit and long lifetime in fluorescent blue OLEDs.…”

40‐3: Distinguished Paper: Realization of Ultra‐High Efficient Fluorescent Blue OLED

“…In SID 2020, we reported that the top emission (TE) device with our BD material with narrow emission band shows high performance in terms of efficiency [8]. In this paper, the top emission device of bilayer EML was fabricated using the narrowband BD and compared with that of the monolayer EML.…”

19‐4: Ultra‐Long‐Life Deep‐Blue OLED Device Achieved by Controlling the Carrier Recombination Site

“…In recent years, the time at which the luminance is reduced by 3 (LT97) or 5 (LT95) from the initial luminance is often used as an indicator of device lifetime that considers display burn-in [1]. A long-life device with an LT95 of approximately 300 h when driven at a constant current density of 50 mA/cm 2 at room temperature has been achieved [2] by, for example, improving the emission layer (EmL) material in a blue fluorescent device. However, a significant luminance decrease that occurs during the initial driving stage, i.e., initial degradation, inhibits further improvements in the LT95.…”