An organic light emitting device, comprising: an anode; a cathode; an emissive layer disposed between the anode and the cathode, the emissive layer further comprising: a first organic layer comprising a first phosphorescent material and a first non-emissive material, wherein the concentration of the first phosphorescent material in the first organic layer is 10 - 90 wt%; and the concentration of the first non-emissive material in the first organic layer is 10 - 90 wt%; a second organic layer comprising a second phosphorescent material and a second non-emissive material, wherein the concentration of the second phosphorescent material in the second layer is 3 - 25 wt%; and the concentration of the second non-emissive material in the second organic layer is 75-97 wt%; wherein the second organic layer is disposed between the first organic layer and the cathode; wherein the concentration of the second phosphorescent material in the second organic layer is lower than the concentration of the first phosphorescent material in the first organic layer; and wherein the first non-emissive material and the second non-emissive material may be the same material or different materials, and the first phosphorescent material and the second phosphorescent material may be the same material or different materials; and one or more third organic layer disposed between the first organic layer and the anode, wherein all organic layers between the first organic layer and the anode have a hole mobility and an electron mobility such that the hole mobility is at least twice as great as the electron mobility, wherein all organic layers between the first organic layer and the anode do not include any materials containing a group selected from the group consisting of triarylamine, napthyl, tri(N-carbazoyl)triphenylamine, tetraarylamine and carbazole. an anode; a cathode; an emissive layer disposed between the anode and the cathode, the emissive layer further comprising: a first organic layer comprising a first phosphorescent material and a first non-emissive material, wherein the concentration of the first phosphorescent material in the first organic layer is 10 - 90 wt%; and the concentration of the first non-emissive material in the first organic layer is 10 - 90 wt%; a second organic layer comprising a second phosphorescent material and a second non-emissive material, wherein the concentration of the second phosphorescent material in the second layer is 3 - 25 wt%; and the concentration of the second non-emissive material in the second organic layer is 75-97 wt%; wherein the second organic layer is disposed between the first organic layer and the cathode; wherein the concentration of the second phosphorescent material in the second organic layer is lower than the concentration of the first phosphorescent material in the first organic layer; and wherein the first non-emissive material and the second non-emissive material may be the same material or different materials, and the first phosphorescent material and the second phosphorescent material may be the same material or different materials; a first organic layer comprising a first phosphorescent material and a first non-emissive material, wherein the concentration of the first phosphorescent material in the first organic layer is 10 - 90 wt%; and the concentration of the first non-emissive material in the first organic layer is 10 - 90 wt%; the concentration of the first phosphorescent material in the first organic layer is 10 - 90 wt%; and the concentration of the first non-emissive material in the first organic layer is 10 - 90 wt%; a second organic layer comprising a second phosphorescent material and a second non-emissive material, wherein the concentration of the second phosphorescent material in the second layer is 3 - 25 wt%; and the concentration of the second non-emissive material in the second organic layer is 75-97 wt%; the concentration of the second phosphorescent material in the second layer is 3 - 25 wt%; and the concentration of the second non-emissive material in the second organic layer is 75-97 wt%; wherein the second organic layer is disposed between the first organic layer and the cathode; wherein the concentration of the second phosphorescent material in the second organic layer is lower than the concentration of the first phosphorescent material in the first organic layer; and wherein the first non-emissive material and the second non-emissive material may be the same material or different materials, and the first phosphorescent material and the second phosphorescent material may be the same material or different materials; and one or more third organic layer disposed between the first organic layer and the anode, wherein all organic layers between the first organic layer and the anode have a hole mobility and an electron mobility such that the hole mobility is at least twice as great as the electron mobility,