STEADY-STATE PHOTOCONDUCTIVITY OF A POLYMER BLEND

The spectral responses of steady state photoconductivity of a polymer blend, poly[2-methoxy,5-(2'-ethyl-hexoxy)-1,4-phenylene vinylene] (MEH -PPV) and ilyl)-1,4-phenylene)-1,2-ethenylene-1,4-phenylene] (called B -polymer) are investigated. Two peaks of photocurrent(PC) at 2.16 eV a nd 3.01 eV are observed under continuous illumination. The peak at 3.0 1 eV is rather broad and has a strong polarity dependence on the appli ed voltage, which could be due to the rectified microjunction formatio n in the polymer blend. The incident beam intensity dependences of the two peaks in PC are I-pc proportional to I-alpha with alpha = 1.05. I t indicates that the monomolecular recombination kinetics is important in this polymer blend. The observed spectral response of PC is discus sed in comparison with the optical absorption as well as the photolumi nescence spectra reported earlier in the same polymer blend.