Color stable phosphorescent white organic light-emitting diodes with double emissive layer structure

Organic light-emitting diodes with a spacer enhanced exciplex emission

“…1-5 On the other hand, OLED lighting development is relatively falling behind. [6][7][8] For high quality OLED lighting, a high color rendering index is required. Generally, a broad band emission spectrum is preferred for high color rendering index.…”

Non-interlayer and color stable WOLEDs with mixed host and incorporating a new orange phosphorescent iridium complex

“…The less intense bands between 350 and 440 nm (e = 5000-12,000 M À1 cm À1 ) can be assigned to an inter ligand charge transfer ( 1 LLCT) and a metal-to-ligand charge transfer (S 0 ? 1 MLCT) [5,13,14]. The iridium complex also shows weak absorption bands above 450 nm (e < 5000 M À1 cm À1 ).…”

“…The main causes leading to color shift in WOLED devices with multiple emitting layers (EMLs) include alteration of recombination zone [11,12], variation of energy transfer situation [13], changing of exciton quenching rate [14,15], as well as electric field or temperature dependent charge mobility [16]. For example, it has been reported that the recombination zone will shift with increasing driving voltage in multi-EML structure when it has a different field-dependent mobility between the hole transporting layer (HTL) and the electron transporting layer (ETL), and/or different carrier trapping situation at the EML [12].…”

Full color organic light emitting diodes with laser-patterned optical path-length compensation layer

“…After this process, stable phosphorescent white OLED based on a double emissive layer was formed by evaporation process and the structure is referred to Ref. [15]. All organic materials were deposited by the vacuum evaporation technique under a pressure of $1 Â 10 À7 Torr.…”