TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Fluorene Moieties: The fluorene moieties are selected from groups of formulae (I) and (II).R1 and R2 = H, 1-20C hydrocarbyl, 1-20C hydrocarbyloxy, 1-20C thiohydrocarbyloxy or CN;R3 and R4 = H, 1-20C hydrocarbyl optionally substituted with Q, 6-20C aryl optionally substituted with Q or form a 3-12C cyclic structures with the olefin carbon to which they are attached. The cyclic structures optionally further contains T;Q = 1-20C alkoxy/aryloxy, thioalkoxy/thioaryloxy, secondary/tertiary amine, hydroxy, carboxylic/sulfonic acid, CN or ester;R5 and R6 = H, 1-20C hydrocarbyl optionally substituted with Q, 6-20C aryl optionally substituted with Q or form 3-12 cyclic structures with the 9C carbon of fluorene. The cyclic structures optionally further contains T; andT = at least one heteroatom such as phosphorus, sulfur, oxygen or nitrogen.Preferred Composition: At least 15% of the monomeric units are the fluorene moieties and at least 10 (preferably 1, especially 5)% of the monomeric units are two moieties which have hole transporting properties and electron transporting properties. The groups having electron transporting properties are from moieties comprising electron-withdrawing groups.    TECHNOLOGY FOCUS - POLYMERS - Preferred Second Polymer: The second polymer comprises monomeric units selected from 9-substituted fluorene moieties and/or 9, 9-disubstituted fluorene moieties. The second is different from the first polymer.Preferred First Polymer: The first polymer is present in an amount of at least 0.1 wt.%.Preferred Copolymer: The copolymer present in the composition comprises the following monomeric units: 9,9-di-hexyl-fluoren-2,7-di-yl, 9,9-di-octyl-fluoren-2,7-di-yl, (III) 4,7-bis(2-thien-5-yl)-2,1,3-benzothiadiazole, 2,1,3-benothiadiazole-4,7-di-yl, or a group of formula (III).    TECHNOLOGY FOCUS - ELECTRONICS - Preferred Component: The anode in the light emitting diode comprises a mixed oxide of tin and indium and the cathode comprises a metallic film. A film comprises at least 0.1 wt.% of the second polymer and the first polymer. The photocell comprising at least one film located between a transparent or semi-transparent first and a second electrode. The light emitting diode comprises a film containing the composition. EXAMPLE - A mixed oxide of tin and indium (ITO)-coated glass, with sheet resistance of about 15 ohms/square, was used as substrate for diode fabrication. The ITO side of the substrate was treated with a 100 nm coating of Baytron P (RTM) (a conducting polymer) diluted with either equal part or two parts of poly(styrene sulfonic acid). The conducting polymer film was dried at 200degreesC in air for about 5 minutes and was then coated with a light emitting polymer film (LEPF) comprising 4 residual monomeric units (RMU) of 9,9-di-hexyl-2,7-bis(1,3,2-dioxaboracyclopentane)-fluorene, 3 RMU of 2,5-di-bromo-2,1,3-benzothiadiazole and 1 RMU of N,N-bis(4-bromophenyl)-N-(4-sec-butyl-phenyl) amine. LEPF was dried in a nitrogen atmosphere at 90degreesC for at least two hours and a calcium cathode (about 75-100 nm) was deposited on it. The finished device was connected to a power source in an inert atmosphere, with ITO being the positive electrode.    A comparative film contained 9,9-di-hexyl-2,7-bis(1,3,2-dioxaboracyclopentane)-fluorene and 2,5-di-bromo-2,1,3-benzothiadiazole but no residual monomeric units. Luminance of emitted light and density of current flowing through the diode were monitored as a function of applied voltage. The efficiency was expressed as lumens/watt (L/W): L/W = p(Cd/A)/V where A and V are the current and voltage for a given brightness.    Thus, volts/L/W for the test sample was 3.9/2.36 and for the comparative was 6.3/0.56 with the luminance of test/comparative being 4000 Cd/m2. The result showed that the luminance of 4000 Cd/m2 was reached at lower voltage and higher efficiency than the comparative sample.