Phosphorescent organic light emitting diodes with high efficiency and brightness
View Patent ↗An organic light emitting device including a) an anode; b) a cathode; and c) an emissive layer disposed between the anode and the cathode, the emissive layer comprising an organic host compound and a phosphorescent compound exhibiting a Stokes Shift overlap greater than 0.3 eV. The organic light emitting device may further include a hole transport layer disposed between the emissive layer and the anode; and an electron transport layer disposed between the emissive layer and the cathode. In some embodiments, the phosphorescent compound exhibits a phosphorescent lifetime of less than 10 μs. In some embodiments, the concentration of the phosphorescent compound ranges from 0.5 wt. % to 10 wt. %.
1. An organic light emitting device comprising:
a) an anode;
b) a cathode;
c) an emissive layer disposed between the anode and the cathode, the emissive layer comprising an organic host compound and a phosphorescent compound exhibiting a Stokes Shift overlap greater than 0.3 eV; wherein the phosphorescent compound exhibits a Stokes Shift overlap integral of less than 50 M −1 cm −1 .
2. The organic light emitting device of claim 1 , wherein the phosphorescent compound exhibits a phosphorescent lifetime of less than 10 μs.
3. The organic light emitting device of claim 1 , wherein the phosphorescent compound further exhibits a triplet-triplet annihilation rate constant of less than 1×10 −12 cm 3 s −1 .
4. The organic light emitting device of claim 1 , further comprising a hole transport layer disposed between the emissive layer and the anode; and an electron transport layer disposed between the emissive layer and the cathode.
5. The organic light emitting device of claim 1 , wherein a concentration of the phosphorescent compound ranges from 0.5 wt. % to 10 wt. %.
6. The organic light emitting device of claim 1 , wherein the device exhibits a peak external quantum efficiency of greater than 8%.
7. The organic light emitting device of claim 5 , wherein the device exhibits a roll off quantum efficiency of 50% of the peak external quantum efficiency at a current density greater than 100 mA/cm 2 .
8. The organic light emitting device of claim 1 , wherein the device exhibits a roll off quantum efficiency of 50% of the peak external quantum efficiency at a current density greater than 100 mA/cm 2 compared to an equivalent device having an emissive layer disposed between the anode and the cathode, the emissive layer comprising an organic host compound and a phosphorescent compound exhibiting a Stokes Shift overlap less than 0.3 eV and a phosphorescent lifetime of less than 10 μs.
9. A method for reducing triplet-triplet annihilation in an organic light emitting device comprising:
providing a device comprising an anode; a cathode; and an emissive layer disposed between the anode and the cathode, the emissive layer comprising an organic host compound and a phosphorescent compound exhibiting a Stokes Shift overlap greater than 0.3 eV; and wherein the phosphorescent compound exhibits a Stokes Shift overlap integral of less than 50 M −1 cm −1 ;
applying a voltage across the anode and the cathode;
wherein the device exhibits a peak external quantum efficiency of greater than 10%; and
wherein the device exhibits a roll off quantum efficiency of 50% of the peak external quantum efficiency at a current density greater than 100 mA/cm 2 .
10. The method for reducing triplet-triplet annihilation in an organic light emitting device according to claim 9 , wherein the phosphorescent compound exhibits a phosphorescent lifetime of less than 10 μs.
11. The method for reducing triplet-triplet annihilation in an organic light emitting device according to claim 9 , wherein the phosphorescent compound further exhibits a triplet-triplet annihilation rate constant of less than 1×10 −12 cm 3 s −1 .