Thickness-Attuned CsPbBr3 Nanosheets with Enhanced p-Type Field Effect Mobility.

Since the invention of field effect transistors (FETs) in the mid-20th century, nanosheet (NS) transistors have been considered the future toward fulfilling Moore's law of scaling. Moving beyond conventional semiconductors, thickness tunable orthorhombic CsPbBr3 NSs are achieved by a perfect control in which the lateral dimension can be extended close to 1 μm. While 18-carbon-chain ligands produce ∼4.5 nm thick NSs, the strongly adsorbed less dynamic 8-carbon-chain ligands result in ∼9.2 nm NSs. Equipped with a minimum trap state density, a lower effective mass of charge carriers, and better carrier transport, the NSs enable an order of magnitude increase in the field effect mobility as compared to that of CsPbBr3 nanocubes, thus revealing the efficacy of designing the two-dimensional morphology. The p-type field effect mobility (μFET) of the photoexcited NSs reaches 10-5 cm2 V-1 s-1 at 200 K upon mitigation of the challenges of ionic screening and constrained tunneling probability across organic ligands.