高效光电调控钙钛矿量子点阻变存储性能

High-Efficiency Photoelectric Regulation of Resistive Switching Memory in Perovskite Quantum Dots

光电阻变存储器(RRAM)因其微型化、集成化和多功能等优点成为下一代非易失性存储器中最有前途的竞争者。采用低温旋涂法合成具有绿色荧光的无机CsPbBr_(3)量子点(QDs)为阻变功能层,制备了高效光电调控的Ag/CsPbBr_(3) QDs/ITO RRAM器件。该器件具有良好的抗疲劳性能和保持特性。在光照触发下,Ag/CsPbBr_(3) QDs/ITO器件的开关比(ON/OFF比)约为3.2×10^(3),较暗态增大了约24倍;写入电压(VSET)为2.88 V,较暗态降低了约13.3%。电场作用下Br−和Ag+双离子迁移形成混合导电细丝的通断是Ag/CsPbBr_(3) QDs/ITO器件阻变的主要机制。经光照激发作用,CsPbBr_(3) QDs薄膜内缺陷密度的减少促进光电流的增大,促进了Ag/CsPbBr_(3) QDs/ITO器件低阻态(LRS)阻值和VSET减小、进而提高器件ON/OFF比。高效光电调控全无机钙钛矿RRAM技术推动了高密度信息存储器的快速发展。

Photoelectric resistive switching memory(RRAM)is the most promising competitor in the next generation of non-volatile memory(NVM)owing to its miniaturization,integration,and versatility advantages.A low-temperature spin coating method is deployed to synthesize inorganic CsPbBr_(3) quantum dots(QDs)with green fluorescence.Then,flexible photoelectrical dual-controlled Ag/CsPbBr_(3) QDs/indium tin oxide(ITO)RRAM devices with high efficiency are prepared,in which the switching behavior is modified by both electric field and light illumination.The as-prepared device demonstrated forming-free bipolar resistive switching behavior in the presence and absence of light.The switching voltages(VSET)show significant reductions compared to the dark condition,and the hysteresis windows considerably increase under illumination.These indicate a higher ON/OFF ratio and lower energy consumption under illumination than in the dark for the Ag/CsPbBr_(3) QDs/ITO device.The ON/OFF ratio of the Ag/CsPbBr_(3) QDs/ITO device is about 3.2×103 under illumination,about 24 times higher than that in the dark state.The VSET is 2.88 V,approximately 13.3%lower than the dark state.These results are further confirmed by the resistive switching behavior of the 36 memory cells randomly selected in the Ag/CsPbBr_(3) QDs/ITO device.Moreover,the devices exhibit good fatigue and retention performance.No noticeable degradation occurre in the high resistance state(HRS)and low resistance state(LRS)even after 500 consecutive cycles.The resistance remain stable for a long retention time exceeding 5000 s.The large ON/OFF ratio,good endurance,and retention properties of the Ag/CsPbBr_(3) QDs:GO/ITO device are sufficient for a photoelectric regulation NVM device.Based on the double logarithmic fitting curves during the switching process,it is assumed that the device has the same conduction mechanism under dark and illumination conditions,which is dominated by both ohmic behavior and space charge limited current(SCLC)mechanism in the HRS,and only by the ohmic conduction in the LRS.The primary resistive switching mechanism in the Ag/CsPbBr_(3) QDs/ITO devices is enabled by the formation and rupture of the hybrid conductive filament composed of Br-vacancies and Ag atom owing to both Br-and Ag+ion migration under an electric field.The main reason for the declining LRS resistance,resulting in the increment of the ON/OFF ratio and VSET of the above devices,is derived from the increasing photocurrent promoted by the decreasing defect density in CsPbBr_(3) QDs films under illumination.High-efficiency photoelectronic regulatory perovskite materials will improve the development of high-density memory RRAM technology.