Photoconducting properties of a ladder polymer

The electronic properties of the ladder polymer BBL are investigated using steady state and transient photoconductivity techniques. The photocurrent response of the polymer film in the surface cell and sandwich cell configurations are compared along with the absorption spectra and the results correlated with the surface and bulk morphology. The steady state photocurrent shows a nonlinear response with respect to the electric field, and the photocurrent spectral response is accompanied by a significant tailing in the infrared region. The photocurrent is also studied as a function of photon intensity and chopper frequency. A long lived transient photocurrent (≳100 ms) is present on exposure to nanosecond laser pulses revealing the presence of deep traps.