Optoelectronic devices

An optoelectronic device comprising a photoresponsive region located between first and second electrodes such that charge carriers can move between the photoresponsive region and the first and second electrodes, the photoresponsive region comprising: a stack of alternate first and second layers, each first layer comprising a first photoresponsive material and each second layer comprising a second photoresponsive material, the first and second photoresponsive materials having different electron affinities; wherein each pair of second layers on opposite sides of a first layer contact each other via first holes defined by said first layer between said pair of second layers, and each pair of first layers on opposite sides of a second layer contact each other via second holes defined by said second layer between said pair of first layers.