Direct comparison of charge transport and electronic traps in polymer–fullerene blends under dark and illuminated conditions

• Charge transport and electronic traps in P3HT:PCBM blends was evaluated in dark and illumination.
• Charge transport properties were analyzed based on current–voltage characteristics measurements.
• Electronic trap density was evaluated by a differential method.
• The charge transport was strongly associated with the trap states distribution.

A direct comparison of charge transport and electronic traps in representative polymer–fullerene blend, poly (3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM), is carried out in dark and illuminated conditions based on the measurements of temperature-dependent current–voltage characteristics. In dark condition, the charge transport presents a transition from Ohmic to trap-limited current. While the trap-filled space charge limited current is observed under illumination at the same applied bias. From evaluations of trap density and energy distribution by a differential method, it is reveal that the diverse charge transport in dark and illuminated conditions is mainly caused by the different trap states distribution, which strongly affects the space charges and the electrical field in P3HT: PCBM blends.

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