Efficient emissive site in organic EL device utilizing 8-hydroxyquinoline aluminium and diamine derivative

Abstract

An efficient emissive site has been investigated by inserting a monolayer size porphine layer (TPP) as a marker in an organic electroluminescent (EL) device consisting of 8-hydroxyquinoline aluminium as an emissive layer and diamine derivative (TPD) as the hole transporting layer. Emissions from and TPP have been observed from the device and the emission intensity from the TPP has been noted to change depending on the distance between the hetero-interface and the inserted site. Emission from the marker layer shows its highest intensity at a position 7 nm from the interface of and TPD. The result also shows that the hetero-interface is not the highest emissive site, but a site several nanometres inside the emissive layer shows the highest emission intensity. The mechanism of emissive recombination has been investigated in an EL device with an emissive layer and a carrier transporting layer.

Exciplex Formations at the HTL/Alq3Interface in an Organic Light-Emitting Diode: Influence of the Electron−Hole Recombination Zone and Electric Field

“…In the HTL/Alq 3 -based OLEDs, the electron−hole recombination zone is located on the Alq 3 side close to the HTL/Alq 3 interface due to the electron transporting nature of Alq 3 and the electron blocking nature of the HTMs. , Because exciplexes are formed only at the interface between the HTL and Alq 3 layer in the HTL/Alq 3 -based OLEDs, the effects of exciplex formation on EL efficiency would be markedly dependent on the concentration of Alq 3 excitons produced at the HTL/Alq 3 interface. The concentration of Alq 3 excitons at the HTL/Alq 3 interface is related to the location and width of the electron−hole recombination zone in the Alq 3 layer.…”

“…These results primarily indicate that electron-hole recombination occurs close to the HTL/Alq 3 interface, which is in good agreement with previous reports. 13,14 The ratio of emission intensity of rubrene to Alq 3 showed some dependence on the HOMO level of the HTM. When x was 0 nm, the ratio of emission intensity of rubrene to Alq 3 for the OLED containing FL1 was slightly lower than that for the OLED containing NPD and FL3.…”

Exciplex Formations between Tris(8-hydoxyquinolate)aluminum and Hole Transport Materials and Their Photoluminescence and Electroluminescence Characteristics

“…The electron−hole recombination zone is located on the Alq 3 side at a point very close to the HTM/Alq 3 interface in HTM/Alq 3 -based OLEDs because of the electron transport nature of Alq 3 and electron blocking nature of HTMs. , Therefore, OLED characteristics are largely affected by intermolecular interaction between Alq 3 excitons and HTM at the HTM/Alq 3 interface. For example, an exciplex EL is observed when low ionization potential materials, such as m -MTDATA, are used as the HTM …”

Organic luminescent devices and magnetoelectronics

“…Cobalt ͑Co͒ and iron ͑Fe͒ were chosen because they have work functions ( Fe ϭ4.5 eV, ITO ϭ4.7 eV, and Co ϭ5.0 eV) 17,22 that straddle that of ITO. All ferromagnetic films were between 100 and 300 Å. Thinner films were used for the up-emitting OLEDs to minimize attenuation of the EL, while still maximizing the magnetic properties.…”