A device, comprising: an anode; a cathode; a first organic emissive layer, further comprising: first phosphorescent material having a concentration of 15-35 wt% in the first organic emissive layer, wherein the first phosphorescent material has a peak emissive wavelength in the visible spectrum at a wavelength between 400 nm and 500 nm; and a first host material having a triplet energy at least 0.2 eV and not more than 1.0 eV greater than the triplet energy of the first phosphorescent material; wherein the first organic emissive layer is disposed between the anode and the cathode; a second organic emissive layer further comprising: a second phosphorescent material having a concentration of 15-35 wt% in the second organic emissive layer, wherein the second phosphorescent material has a peak emissive wavelength in the visible spectrum at a wavelength between 500 nm and 600 nm; a third phosphorescent material having a concentration of 0.1 - 3 wt% in the second organic emissive layer, wherein the third phosphorescent material has a peak emissive wavelength in the visible spectrum at a wavelength between 600 nm and 700 nm; a second host material having a triplet energy greater than that of the third phosphorescent emissive material; wherein the second organic emissive layer is disposed between the anode and the cathode, and is adjacent to the first organic emissive layer; a blocking layer disposed adjacent to the second organic emissive layer and between the second organic emissive layer and the anode, the blocking layer having a lowest unoccupied molecular orbital that is at least 0.1 eV greater than the lowest unoccupied molecular orbital of the second host material; a hole transport layer disposed between the blocking layer and the anode; wherein at least one of the anode and the cathode is transmissive. an anode; a cathode; a first organic emissive layer, further comprising: first phosphorescent material having a concentration of 15-35 wt% in the first organic emissive layer, wherein the first phosphorescent material has a peak emissive wavelength in the visible spectrum at a wavelength between 400 nm and 500 nm; and a first host material having a triplet energy at least 0.2 eV and not more than 1.0 eV greater than the triplet energy of the first phosphorescent material; first phosphorescent material having a concentration of 15-35 wt% in the first organic emissive layer, wherein the first phosphorescent material has a peak emissive wavelength in the visible spectrum at a wavelength between 400 nm and 500 nm; and a first host material having a triplet energy at least 0.2 eV and not more than 1.0 eV greater than the triplet energy of the first phosphorescent material; wherein the first organic emissive layer is disposed between the anode and the cathode; a second organic emissive layer further comprising: a second phosphorescent material having a concentration of 15-35 wt% in the second organic emissive layer, wherein the second phosphorescent material has a peak emissive wavelength in the visible spectrum at a wavelength between 500 nm and 600 nm; a third phosphorescent material having a concentration of 0.1 - 3 wt% in the second organic emissive layer, wherein the third phosphorescent material has a peak emissive wavelength in the visible spectrum at a wavelength between 600 nm and 700 nm; a second host material having a triplet energy greater than that of the third phosphorescent emissive material; wherein the second organic emissive layer is disposed between the anode and the cathode, and is adjacent to the first organic emissive layer; a blocking layer disposed adjacent to the second organic emissive layer and between the second organic emissive layer and the anode, the blocking layer having a lowest unoccupied molecular orbital that is at least 0.1 eV greater than the lowest unoccupied molecular orbital of the second host material; a hole transport layer disposed between the blocking layer and the anode; wherein at least one of the anode and the cathode is transmissive. a second phosphorescent material having a concentration of 15-35 wt% in the second organic emissive layer, wherein the second phosphorescent material has a peak emissive wavelength in the visible spectrum at a wavelength between 500 nm and 600 nm; a third phosphorescent material having a concentration of 0.1 - 3 wt% in the second organic emissive layer, wherein the third phosphorescent material has a peak emissive wavelength in the visible spectrum at a wavelength between 600 nm and 700 nm; a second host material having a triplet energy greater than that of the third phosphorescent emissive material; wherein the second organic emissive layer is disposed between the anode and the cathode, and is adjacent to the first organic emissive layer; a blocking layer disposed adjacent to the second organic emissive layer and between the second organic emissive layer and the anode, the blocking layer having a lowest unoccupied molecular orbital that is at least 0.1 eV greater than the lowest unoccupied molecular orbital of the second host material; a hole transport layer disposed between the blocking layer and the anode; wherein at least one of the anode and the cathode is transmissive.