Improved stability and performance of all inorganic perovskite quantum dots synthesized directly with N-alkylmonoamine ligands for light-erasable transistor memory

Abstract

All inorganic perovskite quantum dots (PeQDs) of CsPbX3 (X = Cl, Br, I, or their mixture) are regarded as promising candidates for photovoltaics and optoelectronic devices owing to their excellent and unique optical and electronic properties. However, their inherent poor stability severely limits their practical applications. Herein, aiming at improving their stability and photoluminescence (PL) properties, a novel surface capping ligand strategy was performed via directly synthesizing CsPbX3 quantum dots (QDs) by hot injection method with straight-chain n-alkylmonoamine instead of conventional organic amine (oleylamine) as ligands. With stronger intermolecular interaction and denser alignment, n-alkylmonoamine ligands would form a stable protective layer on the surface of PeQDs. As a result, the n-alkylmonoamine capped CsPbBr3 QDs exhibited remarkable long-term storage with 70% of PLQY retaining after 30 days in the open air, impressive water resistance for over 1 h in water, significant photostability with hour-scale laser exposure, and high thermal stability with 60% of PLQY retaining after heating at 80 °C for over 60 min. In addition, by blending the CsPbBr3 QDs with polymer as the gate dielectric, novel light-erasable transistor memories were fabricated based on the device architecture of a floating-gate transistor memory (FGOTM). Acting as dense charge tunneling layers for charge trapping materials (PeQDs) in light-erasable transistor memory, the alkylmonoamine ligand layers led to significant broadening of memory windows, presenting various charge capture abilities of the PeQDs with the different capping ligands.