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 poly[1,3-propanedioxy-1,4-phenylene-1,2-ethenyllene-(2,5-bis(trimethylsilyl)-1,4-phenylene)-1,2-etheny lene-I,4-phenylene](called B-polymer) are investigated. Two peaks of photocurrent(PC) at 2.16 eV and 3.01 eV are observed under continuous illumination. The peak at 3.01 eV is rather broad and has a strong polarity dependence on the applied voltage, which could be due to the rectified microjunction formation in the polymer blend. The incident beam intensity dependences of the two peaks in PC are Ipc ∝ Iα with α = 1.05. It indicates that the monomolecular recombination kinetics is important in this polymer blend. The observed spectral response of PC is discussed in comparison with the optical absorption as well as the photoluminescence spectra reported earlier in the same polymer blend.