Optical, electrochemical, and electron-transporting properties of disilane- and siloxane-bridged biphenyl and bithiophene derivatives were investigated, in comparison with those of the monosilane-bridged analogues (siloles). The UV spectra and cyclic voltammograms indicated that elongation of the silicon bridge suppresses the π-conjugation, in accordance with the results of DFT calculations. The DFT calculations indicated also that the disilane-bridged biphenyl and siloxane-bridged bithiophene should have the low-lying HOMOs and LUMOs. The electron-transporting properties were evaluated by the performance of triple-layered OLEDs having vapor-deposited films of the Si-bridged compound, Alq 3 , and TPD, as the electron-transport, emitter, and hole-transport, respectively. Of these, the device with a disilane-bridged biphenyl exhibited the high performance with the maximum current density of 590mA/cm 2 at the applied electric field of 12×10 7 V/m (applied bias voltage=13V) and the maximum luminance of 22000cd/m 2 at 13×10 7 V/m.