Abstract: An organic photo-detecting field-effect device is presented, the device comprising a first layer comprising an organic semi-conducting material, the first layer acting as an accumulation layer and as a charge transport layer for a first type of charge carriers, and a second layer comprising a second material, the second layer acting as a an accumulation layer for a second type of charge carriers. Charges collected in the second layer influence the charge transport in the first layer. The second material may be an organic semi-conducting material or a metal. At the interface between the first layer and the second layer a heterojunction is formed in the case of an organic semi-conducting second material, and a Schottky barrier is formed in the case of a metal second material, giving rise to an efficient exciton splitting. Different geometries and operation modes facilitating the removal of the collected photo-generated charge carriers during the reset period of the device are presented.