We investigate polymer bilayer structures that can be utilized effectively for efficient photovoltaic properties. The transport characteristics of photogenerated free charge carriers across the interface of a bilayer consisting of p-type polymer poly(3-octyl thiophene) (P3OT) or poly(2-methoxy, 5-(2-ethylhexoxy)-1, 4-phenylene vinylene) (MEHPPV) and n-type polymer poly(benzamidazobenzo phenanthroline) (BBL) are studied using photocurrent spectral response, intensity modulated photocurrent spectra, current-voltage, and thermally stimulated current measurements. The parameters governing the device efficiency are controlled by the interfacial defect characteristics and electric field redistribution in the device. A clear evidence of these defect states at the polymer–polymer interface is revealed using the time and frequency domain photocurrent measurements. We compare the figure of merits of the P3OT/BBL and MEHPPV/BBL structures and correlate these properties to the interfacial processes.

Electrical conduction in non-conjugated insulating polymers such as Kapton(R) films was studied as a function of temperature, T (15–500 K) and electric field F (⩽16 kV cm−1). The time dependent isothermal transient currents (ITC) were also studied at different temperatures (15 K

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Electrically active defects have a profound impact on the semiconducting properties of conjugated polymer systems. Defect-induced thermally stimulated current (TSC) in poly (benzimadazobenzophenanthroline), a ladder-type, high-temperature conjugated polymer, is studied in detail. The TSC results identify the nature and the energetics of the trap levels in the polymer. Variations in the results as a function of the initial trap-filling parameters and the thermal history were also observed. The long-lived component in the photoinduced current decay, an indicator of defect states, is also studied within this context. The barrier limiting processes of the photocurrent are correlated with the results obtained from TSC measurements and we speculate on the origin of these defects.