CPC H10K 85/6572 (2023.02) [H10K 50/00 (2023.02); H10K 85/40 (2023.02); H10K 85/654 (2023.02); H10K 2101/30 (2023.02)] | 20 Claims |
1. An organic electroluminescent device comprising a light-emitting layer B comprising:
(i) a first material HB, which has a lowest unoccupied molecular orbital LUMO(HB) having an energy ELUMO (HB) and a highest occupied molecular orbital HOMO(HB) having an energy EHOMO (HB);
(ii) a second material EB, which has a lowermost excited singlet state energy level S1E, a lowermost excited triplet state energy level T1E, a lowest unoccupied molecular orbital LUMO(EB) having an energy ELUMO (EB) and a highest occupied molecular orbital HOMO(EB) having an energy EHOMO (EB); and
(iii) a third material SB, which has a lowermost excited singlet state energy level S1S, a lowermost excited triplet state energy level T1S a lowest unoccupied molecular orbital LUMO(SB) having an energy ELUMO (SB) and a highest occupied molecular orbital HOMO(SB) having an energy EHOMO (SB),
wherein the relations expressed by the following formulas (1) to (2) and either (3a) and (3b) or (4a) and (4b) apply:
S1S≥S1E (1)
T1S≥2.5 eV (2)
ELUMO(EB)<ELUMO(HB) (3a)
0.2 eV<ELUMO(EB)−ELUMO(SB)<0.5 eV (3b)
ELUMO(EB)>ELUMO(HB) (4a)
0.2 eV<ELUMO(HB)−ELUMO(SB)<0.5 eV (4b), and
wherein the mass ratio of second material EB to a third material SB (EB:SB) is >1.
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