Racemic Effect on the Performance of Organic Multilevel Memory: Beyond Molecular Design

Abstract

AbstractImproving organic devices via molecular design is challenging and difficult to rationalize because individual molecular properties always convolute with intermolecular interaction and crystallinity to contribute the device performance. In this work, it is demonstrated for the first time that racemic effect can be utilized to effectively improve memory device performance. A pair of enantiomers and their mixture are used to prepare organic multilevel resistive random access memory (RRAM) devices. The RRAM devices fabricated from the equimolar mixture of enantiomers are of the lowest onset voltages and highest ternary device yield, independent of the preparation methods. Structural analysis of the powder, film, and single crystal of the equimolar mixture reveals formation of a real racemic compound, where π–π stacking in contrast to the only C–H–π interaction in the film of pure enantiomers appears. Since individual enantiomer has identical electronic properties, the discrepancy in device performance is attributed to the different intermolecular interactions.