Facile and one-step processible CdSe/ZnS quantum dots and pentacene-based nonvolatile memory device

In this study, we propose an organic memory device using CdSe/ZnS quantum dots (QDs) and a pentacene blending solution as a charge storage layer with a one-step process. The QDs were localized without any tunneling insulators and were used as hole-trapping sites. Moreover, the QDs and pentacene blending solution formed a type II junction, assisting in the facilitation of energy band bending. The band bending inhibited the back-injection of the holes trapped in the CdSe (core of QDs) into an electrode, thereby developing a hysteretic I-V response during device operation. The synthesized QDs had a photo-luminance peak at 535 nm (Green QDs). The fabricated memory device had a structure of <ITO/ PVP/ CdSe-ZnS QDs @pentacene/Al> and exhibited current differences (approximately 300 times the ON/OFF ratio) at 0.5 V. The device was fabricated using the spin-coating method. The write voltage was approximately 2.5 V. The erasing process was performed by applying a voltage of approximately −4 V. In addition, the stored charge retained its initial value even after 150 h and the write voltage was maintained after 200 write/erase cycles; the long retention time and high durability will be advantageous for future applications of nonvolatile memory.