Organic electroluminescent materials and devices

A composition comprising a mixture of wherein the first compound (W1) and the second compound (W2) are differently selected from the group comprising:

• (1) a first dopant D1 that is a phosphorescent material or a fluorescent material in an OLED at room temperature
• (2) a first host H1;
• (3) a second host H2;
• (4) a third host H3;
• and
• (5) an acceptor A1;
• wherein the first compound has an evaporation temperature T1 of 150 to 450° C.;
• wherein the second compound has an evaporation temperature T2 of 150 to 450° C.;
• wherein absolute value of T1-T2 is less than 20° C.

A method for fabricating an organic light emitting device (OLED), the method comprising:

• providing a substrate having a first electrode disposed thereon;
• depositing a first organic layer over the first electrode by evaporating a composition comprising a mixture of a first compound (W1) and a second compound (W2) in a high vacuum deposition tool;
• and
• depositing a second electrode over the first organic layer,
• wherein the first compound and the second compound are differently selected from the group comprising:
• (1) a first dopant D1 that is a phosphorescent material or a fluorescent material in an OLED at room temperature
• (2) a first host H1;
• (3) a second host H2;
• (4) a third host H3;
• and
• (5) an acceptor A1;
• wherein the first compound has an evaporation temperature T1 of 150 to 450° C.;
• wherein the second compound has an evaporation temperature T2 of 150 to 450° C.;
• wherein absolute value of T1-T2 is less than 20° C.