Details

Autor(en) / Beteiligte

• Afolayan, Emmanuel O.
• Dursun, Ibrahim
• Lang, Chao
• Pakhomenko, Evgeny
• Kondakova, Marina
• Boroson, Michael
• Hickner, Michael
• Holmes, Russell J.
• Giebink, Noel C.

Titel

Reducing Spontaneous Orientational Polarization via Semiconductor Dilution Improves OLED Efficiency and Lifetime

Ist Teil von

• Physical review applied, 2022-05, Vol.17 (5), Article L051002

Ort / Verlag

United States: American Physical Society (APS)

Erscheinungsjahr

2022

Quelle

APS_美国物理学会期刊

Beschreibungen/Notizen

• Spontaneous orientational polarization (SOP) in the electron-transport layer (ETL) of organic light-emitting diodes (OLEDs) is increasingly recognized as a key factor influencing their performance. Here, we show that SOP is dramatically reduced in the common electron-transport material 2,2',2"-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) by coevaporating it together with medium-density polyethylene. Eliminating SOP from the ETL of blue fluorescent OLEDs in this manner reduces their operating voltage by 0.5 V, increases their external quantum efficiency (EQE) by 30%, and leads to a threefold increase in device lifetime. We show that the EQE and lifetime improvements both originate from reduced exciton-polaron annihilation in the emissive layer, and that this leads to a functional relationship between the two quantities that can be used to quantify the rate of annihilation-induced degradation in the device. Furthermore, these results highlight a substantial opportunity to improve OLED performance by controlling SOP through semiconductor dilution and suggest that this capability can be used to systematically isolate and understand exciton-polaron degradation in the pursuit of stable blue OLEDs.