TECHNOLOGY FOCUS - ELECTRONICS - Preferred Components: In the device: a layer comprising a conducting polymer is disposed at least between one electrode and the light emitting layer such that the layer comprising a conducting polymer is adjacent to the electrode; an insulation layer having a thickness of 2 nm or less is disposed at least between one electrode and the light emitting layer such that the insulation layer is adjacent to the electrode; a layer comprising an electron transporting compound is disposed between the cathode and the light emitting layer such that the layer comprising an electron transporting compound is adjacent to the light emitting layer; a layer comprising a hole transporting compound is disposed between the anode and the light emitting layer such that the layer comprising a hole transporting compound is adjacent to the light emitting layer.    TECHNOLOGY FOCUS - POLYMERS - Preparation: No preparation method is given. EXAMPLE - 1,4-Dibromo-2,5-di(3,7-dimethyloctyloxy)benzene (0.62 g), N,N'-diphenyl-N,N'-di(3-methyl-4-bromophenyl)benzidine (0.25 g) and 2,2'-bipyridyl (0.55 g) were charged in a reaction vessel, then, the atmosphere in the reaction system was purged with an argon gas. To this was added toluene (40 ml) deaerated previously by bubbling of an argon gas. Then, to this mixed solution was added bis(1,5-cyclooctadiene)nickel (0) (0.96 g), and the mixture was stirred for 10 minutes, then, they were reacted at 60 degrees C for 7 hours. The reaction was conducted in an argon gas atmosphere. After the reaction, this solution was cooled, then, poured into a mixed solution of 25% ammonia water (10 ml)/methanol (150 ml)/ion exchanged water (50 ml), and the mixture was stirred for 1 hour. Then, this mixed solution was allowed to stand still, to find separation into two layers. The upper layer was recovered, this solution was poured into methanol to cause re-precipitation, and the produced precipitation was recovered. This precipitation was dried, then, dissolved in chloroform. This solution was filtrated to remove insoluble materials, then, this solution was poured into methanol to cause re-precipitation, and the produced precipitation was recovered. This precipitation was dried under reduced pressure to obtain polymeric fluorescent substance (0.22 g) comprising 2,5-bis-(3,7-dimethyl-octyloxy)-phen-1,4-diyl and N4,N4'-bis(3-methylphen-4-yl)-N4,N4'-diphenylbiphenyl-4,4'-diamine repeating units in molar ratio of (75/25), and having a polystyrene reduced number-average molecular weight of 1.7x 104 and a polystyrene reduced weight-average molecular weight of 1.3x 105.