First and second electrodes (3 and 4) are provided on respective ones (2' and 2") of the first and second major surfaces of a photoresponsive zone (2). The photoresponsive zone (2) is in the form of a polymer blend having regions (2a) of a first semiconductive polymer and regions (2b) of a second...http://www.google.co.uk/patents/US5670791?utm_source=gb-gplus-sharePatent US5670791 - Photoresponsive device with a photoresponsive zone comprising a polymer blend 
