Effective intermediate layers for highly efficient stacked organic light-emitting devices

Abstract

Effective intermediate electrode layers comprising of LiF(1nm)∕Ca(25nm)∕Ag(15nm) or LiF(1nm)∕Al(3nm)∕Au(15nm) were studied in stacked organic light-emitting devices (OLEDs). Stacked OLEDs with two identical emissive units consisting of NPB∕Alq3: C545T/BCP exhibited superior luminous efficiency-current density characteristics over conventional single-unit devices. At 20mA∕cm2, the luminous efficiency of the stacked OLEDs using the intermediate layers of LiF∕Ca∕Ag and LiF∕Al∕Au were about 19.6cd∕A and 17.5cd∕A, respectively, almost doubling that of the corresponding control devices, as expected.

Polymeric tandem organic light-emitting diodes using a self-organized interfacial layer

“…[1][2][3][4][5] The chemical charge transfer between alkali or alkaline earth metals and organic material can also create free charge carriers in the interfacial layer. [1][2][3][4][5] However, in polymeric tandem OLEDs, the performance enhancement mechanism seems to be quite different from that in stacked small molecule tandem OLEDs. The dot-formed interfacial layer's role is just charge blocking and accumulation of both holes and electrons, not the spouting zone.…”

“…[1][2][3][4][5] A strong electric field from an externally applied voltage assists with generating a number of free charge carriers of both electrons and holes from the bounded electron-hole pairs by the Onsager theory, 2 to reduce the potential barrier between the stacked structures. [1][2][3][4][5] The chemical charge transfer between alkali or alkaline earth metals and organic material can also create free charge carriers in the interfacial layer. [1][2][3][4][5] However, in polymeric tandem OLEDs, the performance enhancement mechanism seems to be quite different from that in stacked small molecule tandem OLEDs.…”

23.2: An Efficient Stacked OLED with Double-Sided Light Emission

“…The detailed cleaning procedures of substrates are the same with and can be referred to the previous report [13]. Organic materials including 4,4',4''-tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine (m-MTDATA); N,N' -di(naphthalene-1-yl)-N,N' -diphenyl-benzidine (NPB); tris(8-hydroxyquinoline) aluminium(III) (Alq 3 ); 10-(2-benzothia zolyl) -1,1,7,7-tetramethyl-2,3,6,7-tetrahydro 1H,5H,11H -benzo [1]pyrano [6,7,8-ij]quinolizin-11-one (C545T) and 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) were all used as received (from LumTec Corp.) without further purification.…”

An effective intermediate Al/Au electrode for stacked color-tunable organic light emitting devices

“…Al/Au structures can potentially provide good carrier injection and optical properties along with offering device stability for top-emission and stacked OLEDs [13,14] potentially. It is because Al/LiF is a good cathode with good electron injection [15] whereas Au is a good anode material for its high work function (5.0eV). In addition, thin Al/Au film is semi-transparent while it keeps high conduction and good contact properties with organic materials.…”