A solution-processable triphenylamine-fluorene host for exciplex based white phosphorescent organic light-emitting diodes

A Bulky Pyridinyl?uorene/Triphenylamine Hybrid Used as Host Material for Heavily‐Doped Blue Electrophosphorescent Devices

“…[14,15] To date, triphenylamine (TPA) and carbazole derivatives are most widely employed as host materials for PhOLEDs due to their high triplet energy level, sufficient hole transporting property, and wide energy gap. [16] Nevertheless, the twisted molecule structure of TPA is detrimental to obtain host materials with high thermal and morphological stabilities. [16] Therefore, many efforts have been made to improve thermal and morphological stabilities with high triplet energy level of the TPA host.…”

“…[16] Nevertheless, the twisted molecule structure of TPA is detrimental to obtain host materials with high thermal and morphological stabilities. [16] Therefore, many efforts have been made to improve thermal and morphological stabilities with high triplet energy level of the TPA host. For example, in order to optimize rigid triphenylamine structure, Shu and his group developed a facile synthesis method of a novel fluorene/triarylamine hybrid (tris-[4-(9-phenylfluoren-9-yl)-phenyl]amine, TFTPA) with high thermal and glass transition temperatures of 491 and 186 ℃, respectively.…”

White Polymer Light-Emitting Diodes Based on Exciplex Electroluminescence from Polymer Blends and a Single Polymer

“…Solution-processable white polymer light-emitting diodes (WPLEDs) have attracted tremendous interest due to their great potential for applications in flat-panel displays, and as back-lighting sources for liquid-crystal and solid-state light sources. − To realize efficient white light-emission, one needs to simultaneously involve certain proportions of three primary colors (blue, green, and red) or two complementary colors (blue with orange or yellow) in the emissive layer . In this respect, various strategies have been utilized to attain white light-emission, such as physically blending the monochromic emitters into the host polymeric materials, or chemically tethering light-emitting species into polymer chains. − From the perspective of device engineering, multilayered WPLEDs are highly favorable because they can allow for the independent contribution of each single layer to either charge-injection or light-emission. , However, the intermediate bimolecular excited state (exciplex) may be formed at the interface of a hole-dominant and an electron-dominant layer, for which the electron and hole are confined in the interface of such two layers. − Exciplex is fundamentally unfavorable for the attainment of high color purity of the monochromic color due to its broad emission profile. − However, when it comes to white light-emission with multicomponent characteristics, exciplex can be potentially utilized as a low-energy emissive species to compensate for the high-energy blue emission for the achievement of white light-emission. ,− …”

Solution-processed thermally stable amorphous films of small molecular hole injection/transport bi-functional materials and their application in high efficiency OLEDs

“…7 Functional characteristics such as the energy levels of the polymers depend not only on the unit structure, but also on the length of the polymer chain which is not a constant. [8][9][10] It is believed that the design, synthesis and purification of small molecular materials are more convenient.…”