Organic electroluminescent materials and devices

An organic light emitting device (OLED) comprising:

• an anode;
• a cathode;
• and
• an emissive region disposed between the anode and the cathode;
• wherein the emissive region comprises:
• a compound S1;
• a compound A1;
• and
• a compound H1;
• wherein the compound S1 is a sensitizer that transfers energy to the compound A1;
• wherein the compound A1 is an acceptor that is an emitter;
• and
• wherein the compound H1 is a host that is the only host in the emissive region.

A composition comprising a first compound and a second compound;

• wherein the first compound and the second compound are differently selected from the group consisting of:
• (1) a compound S1 being a sensitizer that transfers energy to an acceptor A1;
• (2) the compound A1 being an acceptor that is the emitter in the OLED at room temperature;
• (3) a compound H1 being a host in the OLED at room temperature;
• 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.;
• and
• wherein absolute value of T1−T2 is less than 20° C.

A method of deuterating an aromatic compound, comprising:

• providing a catalyst;
• activating the catalyst with a mixture comprising an activator and D2O at a temperature of at least 100° C.;
• and
• contacting the activated catalyst with a uniform mixture comprising an aromatic compound and D2O, wherein hydrogen-substituted aromatic ring atoms of the aromatic compound are deuterated during the contacting step.