and the pixel defining layer 131 the uv rays transmitted through the light transmitting portion 211 of the optical mask 201 then modify a surface of the first medium layer forming coating film 141 p thus a region of the first medium layer forming coating film 141 p corresponding to the light shielding portion 221 remains as the first region 141 b while a region of the first medium layer forming coating film 141 p corresponding to the light transmitting portion 211 is modified to the second region 141 a accordingly the first medium layer 141 including the first region 141 b and the second region 141 a is completed in some other embodiments of the present invention the first medium layer forming coating film 141 p has the same property as the second region 141 a e g relatively low wettability and is then modified to have the same property as the first region 141 b e g relatively high wettability with uv radiation in this case the arrangement of the light shielding portion 221 and the light transmitting portion 211 is reversed in the optical mask 201 referring to fig1 the pixel defining layer 131 is formed on the first region 141 b on the substrate 110 the pixel defining layer 131 may be printed for example using nozzle printing or inkjet printing referring to fig1 the light emission layer 150 is formed by printing an organic light emission material on the first region 141 b on the first electrode 120 here the pixel defining layer 131 may be used as a printing barrier next referring to fig1 a second medium layer 171 and a second electrode 181 are formed.