Enhancement of memory margins for stable organic bistable devices based on graphene-oxide layers due to embedded CuInS2 quantum dots

Current–voltage (I–V) curves for Al/CuInS2 (CIS) quantum dots (QDs) embedded in graphene-oxide layer/indium-tin-oxide devices at 300 K 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 × 105 s, indicative of the memory stability of the OBDs. I–V curve at lower voltages up to 0.05 V was attributed to the thermionic emission mechanism, and the curve in the applied voltage range from 0.06 to 0.17 V was related to an ohmic mechanism. The I–V characteristics in the applied voltage above 0.18 V dominantly followed the space-charge-limited-current behaviors.