Enhancement of memory margins for stable organic bistable devices based on graphene-oxide layers due to embedded CuInS 2 quantum dots

Current–voltage (I–V) curves for Al/CuInS2 (CIS) quantum dots (QDs) embedded in graphene-oxide layer/indium-tin-oxide devices at 300K showed a current bistability with a maximum high conductivity (ON)/low conductivity (OFF) ratio of 1×104, which was 100 times larger than the ON/OFF ratio of the device without CIS QDs. I–V curves and write-read-erase-read voltage cycles demonstrated the rewritable nonvolatile memory properties of the organic bistable devices (OBDs) with ON and OFF current states at the same voltage. The retention time was above 1×105s, indicative of the memory stability of the OBDs. I–V curve at lower voltages up to 0.05V was attributed to the thermionic emission mechanism, and the curve in the applied voltage range from 0.06 to 0.17V was related to an ohmic mechanism. The I–V characteristics in the applied voltage above 0.18V dominantly followed the space-charge-limited-current behaviors.