Nongeminate carrier recombination rates in organic solar cells

Ambipolar organic thin-film transistors and lateral resistor structures have been used to study the transport of charge carriers in bulk heterojunction (BHJ) organic photovoltaic devices. Active layers of a phase-separated blend of poly(3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyl ester were chosen due to their wide use in BHJ solar cell devices. A new method for determining nongeminate recombination rates is reported. Field dependent measurements of the recombination rate show that recombination decreases with increasing electric field.