The emissive substance included in the device is at least one of the following types of compounds: {HEAD ~ a compound} having {TAIL ~ a plurality} of 1,7 phenanthroline skeletal structures; a benzoquinoline derivative; a spiro compound; and a tetraphenylmethane derivative 
having
The emissive substance included in the device is at least one of the following types of compounds : { HEAD ~ a compound } having { TAIL ~ a plurality } of 1,7 phenanthroline skeletal structures ; a benzoquinoline derivative ; a spiro compound ; and a tetraphenylmethane derivative
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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 OTH OTH