[en] An ultrafast pump-probe spectroscopy was used to investigate the transient phenomena of the excitons induced by the electric field to gain an insight into the effect of electric field on the organic light emission diode. At high excitation density of 230 μJ/cm² the decay of the singlet excitons showed fast and slow components. The amplitude factor and the relaxation time of the fast component are field-dependent. The slow component is field-independent, and its relaxation time-constant is about 890 ps. We also observed the longitudinal acoustic phonons with sound velocity of 17 A/ps generated by excitation pulse.