Lattice marginal reconstruction-enabled high ambient-tolerance perovskite quantum dot phototransistors

Perovskite quantum dots (PeQDs) have been rapidly developed as photoactive materials in hybrid phototransistors because of their strong light absorption, broad bandgap customizability, and defect tolerance in charge-transport properties. The solvent treatment has been well recognized as a practical approach for improving the charge transport of PeQDs and the photoresponsivity of PeQD phototransistors. However, there is a lack of fundamental understanding of the origin of its impacts on the ambient stability of the material, as well as the operational lifetime of the phototransistor. In particular, the relationship between the surface ligand dissociation and the microstructural reconstruction has not been fully elucidated so far. Herein, we report that a simultaneous enhancement of the photoresponsivity and ambient tolerance for PeQD-based hybrid phototransistors can be realized via medium-polarity-solvent treatment on solid-state PeQDs. Our comprehensive optoelectronic characterization and electron microscopic study reveals that the crystal morphology, instead of the surface ligands, is the dominating factor that results in the stability enhancement of the PeQDs. This stability enhancement is associated with the preservation of the optical property and quantum confinement. In addition, we unveil a marginal reconstruction process that occurred during solvent treatment, which opens up a new route for the facetoriented attachment of PeQDs along the h220i zone axis to suppress the damage from water molecule penetration. Our study yields a new understanding of the solvent impact on the PeQD microstructure reconstruction, and suggests new routes for perovskite materials and corresponding device operational stability enhancement.