Synthesis, properties, and electrical memory characteristics of new diblock copolymers of polystyrene-block-poly(styrene-pyrene)

In this study, we report the synthesis, properties, and electrical memory characteristics of new diblock copolymers, polystyrene-block-poly(styrene-pyrene) (PS-b-P(St-Py)), prepared by combining atom transfer radical polymerization and Suzuki coupling reaction. The effects of the St?CPy block chain length on the electronic energy level, photophysical properties, and memory characteristics were explored. The PS₄₂-b-P(St-Py)₁₀₈ and PS₆₆-b-P(St-Py)₆₇ devices exhibited a dynamic random access memory characteristics with different turn-on threshold voltages of ?2.7 and ?3.1?V, respectively. Moreover, these memory devices showed a high ON/OFF current ratio of 10⁹ and were electrically stable for at least 10⁴?s in both ON and OFF states. However, the PS₁₁₃-b-P(St-Py)₄₅-based device displayed an insulating state in a low current variation of 10^?12 to 10^?14?A, which had a short St?CPy block length. The mechanism of the switching behavior was explained by the charge hopping conduction between the pyrene units with coexisting charge-trapping environment. The volatility of the memory effect was depended on the ability of charge trapping/back transferring of trapped charge. The present study suggested that the electrical memory characteristics could be efficiently tuned through the block ratio between insulating segment and pendant-conjugated segment of the diblock polymers.