Regulating the perovskite nanocrystal allocations in carbohydrate block copolymers through architecture engineering for nonvolatile phototransistor memory

Abstract

With the numerous merits and the extensive application of perovskite (PVSK), the exponential research efforts have committed themselves to it in this era. Although most focus on finding approaches to address these two challenging issues of environmental stability and spatial dispersity, there has been no investigation of the impact of block copolymer (BCP) architectures on the performance of photomemory devices based on PVSK floating gates. Herein, this study explores carbohydrate-based BCPs to passivate the PVSKs. The dispersion of the CsPbBr₃ PVSKs is improved by a series of diblock and triblock BCPs comprising polydimethylsiloxane (PDMS) and maltoheptaose (MH). Benefitting from the strong hydrophobicity of PDMS blocks and strong hydrophilicity of sugar blocks, the resulting synthetic polymers form as high-χ BCPs, where χ is the Flory–Huggins interaction parameter. In addition, the wealthy hydroxy groups of sugar blocks interact with the PVSK precursors, which instantaneously control the crystallization growth by self-assembly microstructures. The PVSK/BCP nanocomposite films exhibit good optical performance, strong photoluminescence emission, a long exciton lifetime, an efficient charge transfer, excellent morphological topography, and optimal crystallinity of PVSK nanocrystal well-dispersed in the polymeric matrix. As an aspect of the application, the photomemory device based on the triblock BCP comprising PDMS and MH outperforms the diblock counterparts on long-term memory behavior, giving a high memory ratio > 10⁴ over 10,000 s and high stability after 40 endurance cycles. In conclusion, the carbohydrate-based BCPs utilized as a floating-gate layer in photomemory with a photo-writing/electrical-erasing program show conspicuous data discrepancy, stable digital capacity, and decent switchability. The results indicate that the high-χ BCP architecture and polar group contents play an essential role in PVSK allocations, thereby boosting the photoresponse and stability in phototransistor memory.