In-plane electrical bistability of photochromic diarylethene/Cu composite film

Abstract

Electrical bistability is an essential property for memory devices. We report here the in-plane electrical bistability of photochromic diarylethene (DAE)/Cu composite film, which is prepared by Cu vapor deposition on the DAE surface with a low glass-transition temperature. The low-current level around 10−8A was switched to a high-current level of ca. 10−4A at a low threshold voltage (Vth) in the first voltage sweep. Once this switching occurred, the high-current level was kept in the second voltage sweep, and electrical bistability was achieved for the in-plane current. Vth was distributed in a wide range of voltages (0.5–10V), and the colored sample obtained by the UV irradiation showed a relatively higher Vth than the colorless sample. The highest ON–OFF ratio in current was ca. 106. The origin of the bistability attributed to the electrical breakdown in the insulated lines that was consisted of DAE in Cu film. The in-plane bistability of the DAE/Cu composite film has good retention time (>60min) and readout-cycle endurance (>106 cycles), indicating that it is suitable for write-once organic semiconductor memory characteristics.