Electromodulation of photoinduced charge transfer in polyfluorene bilayer devices

Photoinduced charge transfer at a conjugated polymer donor-acceptor heterojunction controls the ultimate photogeneration efficiency in photovoltaic devices. We have studied this charge transfer by measurements of electric-field-induced photoluminescence (PL) modulation in polyfluorene-based bilayer devices at room and low temperatures. Depending on the field direction across the interface we observe field-induced quenching or enhancement of the PL, which we ascribe to modulation of the exciton dissociation rate through modification of the energy of the charge-transfer state formed after charge separation. (C) 2004 American Institute of Physics.