{HEAD ~ The initial OLEDs} used {TAIL ~ emissive molecules} that emitted light from their singlet states as disclosed, for example, in U.S. Pat 
used
{ HEAD ~ The initial OLEDs } used { TAIL ~ emissive molecules } that emitted light from their singlet states as disclosed , for example , in U.S. Pat
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH