According to an embodiment of the present invention, an OLED display includes a substrate, a first electrode, a hole transport layer, a hole blocking layer, an emitting layer, and a second electrode. The first electrode is formed on the substrate. The hole transport layer is formed on the first electrode and includes a first material having a first highest occupied molecular orbital (HOMO) level and a first lowest unoccupied molecular orbital (LUMO) level. The hole blocking layer is formed on the hole transport layer and includes a second material having a second HOMO level and a second LUMO level. The emitting layer is formed on the hole blocking layer and includes a third material having a third HOMO level and a third LUMO level. The second electrode is formed on the emitting layer. Herein, the second HOMO level is higher than the first HOMO level and the third HOMO level.