Synthesis of polymers with alternating organosilanylene and oligothienylene units and their optical, conducting, and hole-transporting properties

Polymers with alternating mono-, di-, or trisilanylene units and 2,5-oligot hienylene groups, [(SiR2)(x)(C4H2S)(m)](n) (R = Me, Et, x = 1-3, m = 2-5), were synthesized and their optical, conducting, and hole-transporting prope rties were investigated. The UV absorption and emission maxima of the polym ers shift to lower energies as the number of thienylene groups (m) between the silanylene units increases, while they are little affected by the silic on chain length (x). When the polymer films were exposed to FeCl3 vapor, se miconducting films with the conductivities of 1.3 x 10(-4)-2.3 x 10(-1) S/c m were obtained. The conductivities tend to increase with m but decrease wi th increasing x. The double-layer-type EL devices were fabricated using som e of the polymers (x = 1, m = 3-5; x = 2, n m = 4) as the hole-transporting layer and tris(8-quinolinolato)aluminum(III) (Alq) as the electron-transpo rting-emitter layer. Reducing the number of m and x resulted in a high-volt age shift in the turn-on voltage and a decrease in the maximum current dens ity of the device. The highest luminance of 2000 cd/m(2) was obtained from a device based on the disilanylene-tetrathienylene alternating polymer (x = 2, m = 4).