Method of forming an organic light emitting display apparatus, comprising: forming an anode on a substrate; forming a light-emitting unit over the anode, the light-emitting unit comprising a first emission layer, a first electron transporting layer, and a first hole transporting layer comprising a mixed layer having a first material and a second material, a first non-mixed layer having only the first material, and a second non-mixed layer having only the second material, the forming the first hole transporting layer comprising: arranging a first evaporator provided with the first material and a second evaporator provided with the second material together at a lower side of a chamber; moving the substrate with the anode facing the first evaporator and the second evaporator along a direction of the chamber while the first material is evaporated from the first evaporator and the second material is evaporated form the second evaporator in such a way that the first material evaporated from the first evaporator is deposited first on the substrate, to thereby form the first non-mixed layer, a mix of the first material and the second material is deposited thereafter as the mixed layer on the first non-mixed layer, and the second material evaporated from the second evaporator is deposited thereafter on the mixed layer, wherein the first material has a higher hole mobility than the second material, the second material has a higher triplet energy level than the first material, and the second material has a lower highest occupied molecular orbitals (HOMO) level than the first material; and forming a cathode. forming an anode on a substrate; forming a light-emitting unit over the anode, the light-emitting unit comprising a first emission layer, a first electron transporting layer, and a first hole transporting layer comprising a mixed layer having a first material and a second material, a first non-mixed layer having only the first material, and a second non-mixed layer having only the second material, the forming the first hole transporting layer comprising: arranging a first evaporator provided with the first material and a second evaporator provided with the second material together at a lower side of a chamber; moving the substrate with the anode facing the first evaporator and the second evaporator along a direction of the chamber while the first material is evaporated from the first evaporator and the second material is evaporated form the second evaporator in such a way that the first material evaporated from the first evaporator is deposited first on the substrate, to thereby form the first non-mixed layer, a mix of the first material and the second material is deposited thereafter as the mixed layer on the first non-mixed layer, and the second material evaporated from the second evaporator is deposited thereafter on the mixed layer, wherein the first material has a higher hole mobility than the second material, the second material has a higher triplet energy level than the first material, and the second material has a lower highest occupied molecular orbitals (HOMO) level than the first material; and forming a cathode. arranging a first evaporator provided with the first material and a second evaporator provided with the second material together at a lower side of a chamber; moving the substrate with the anode facing the first evaporator and the second evaporator along a direction of the chamber while the first material is evaporated from the first evaporator and the second material is evaporated form the second evaporator in such a way that the first material evaporated from the first evaporator is deposited first on the substrate, to thereby form the first non-mixed layer, a mix of the first material and the second material is deposited thereafter as the mixed layer on the first non-mixed layer, and the second material evaporated from the second evaporator is deposited thereafter on the mixed layer, wherein the first material has a higher hole mobility than the second material, the second material has a higher triplet energy level than the first material, and the second material has a lower highest occupied molecular orbitals (HOMO) level than the first material; and forming a cathode.