In organic memory devices, we introduce non-interacting "write" and "read" processes so that the state of a device is not perturbed during the "read" process. We have used heterojunction devices based on suitable materials in such a way that they can generate photovoltage and photocurrent upon illumination. Both open-circuit voltage or short-circuit current of the device have responded to conductance switching. We have showed that the device can be switched to a high-conducting state by applying a suitable voltage pulse and its state can be probed or "read" by measuring open-circuit voltage or short-circuit current. The results show newer parameters to probe organic memory devices. © 2008 Elsevier B.V. All rights reserved.