Abstract
Mixed halide perovskite materials are actively researched for solar cells with high efficiency. Their hysteresis which originates from the movement of defects make perovskite a candidate for resistive switching memory devices. We demonstrate the resistive switching device based on mixed-halide organic-inorganic hybrid perovskite CH3NH3PbI3−xBrx (x = 0, 1, 2, 3). Solvent engineering is used to deposit the homogeneous CH3NH3PbI3−xBrx layer on the indium-tin oxide-coated glass substrates. The memory device based on CH3NH3PbI3−xBrx exhibits write endurance and long retention, which indicate reproducible and reliable memory properties. According to the increase in Br contents in CH3NH3PbI3−xBrx the set electric field required to make the device from low resistance state to high resistance state decreases. This result is in accord with the theoretical calculation of migration barriers, that is the barrier to ionic migration in perovskites is found to be lower for Br− (0.23 eV) than for I− (0.29–0.30 eV). The resistive switching may be the result of halide vacancy defects and formation of conductive filaments under electric field in the mixed perovskite layer. It is observed that enhancement in operating voltage can be achieved by controlling the halide contents in the film.
Highlights
Improving operating voltage of MAPbI3 has been achieved by substitution of I− with Br−, which arises from low activation barrier of Br vacancy
Au/CH3NH3PbI3−xBrx/I migrates toward the electrode (ITO)-coated glass is used to demonstrate memory devices that have a metal/insulator/ metal (MIM) structure. (Fig. 1a) Through the replacement of I− with Br−, the color of the film changed from semi-transparent dark brown (CH3NH3PbI3) to light brown (CH3NH3PbI2Br, CH3NH3PbIBr2) to yellow (CH3NH3PbBr3) with increasing Br content. (Fig. 1b)
In CH3NH3PbI3, the main (110) diffraction peak of perovskite occurs at 14.18°; as Br− progressively replaced I− in CH3NH3PbI3, this diffraction peak shifted to 14.44° in CH3NH3PbI2Br, 14.66° in CH3NH3PbIBr2, and 14.98° in CH3NH3PbBr3
Summary
Improving operating voltage of MAPbI3 has been achieved by substitution of I− with Br−, which arises from low activation barrier of Br vacancy. The fabricated Au/CH3NH3PbI3−xBrx/ITO memory device shows low voltage operation, long data retention, and good endurance. Based on measured current electric field responses, we propose possible resistive switching mechanisms that involve migration of Br− and I− vacancies. We demonstrated first-principles density functional theory (DFT) calculations to clarify the lower ionic migration barrier for bromide vacancy than for iodine vacancy which leads to decreased electric field as Br content increases.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
