Charge Transport between Coupling Colloidal Perovskite Quantum Dots Assisted by Functional Conjugated Ligands

Long alkyl-chain capping ligands are indispensable for preparing stable colloidal quantum dots. However, its insulating feature blocks efficient carrier transport among QDs, leading to inferior performance in light-emitting diodes (LEDs). The trade-off between conductivity and colloidal stability of QDs has now been overcome. Methylamine lead bromide (MAPbBr₃) QDs with a conjugated alkyl-amine, 3-phenyl-2-propen-1-amine (PPA), as ligands were prepared. Owing to electron cloud overlapping and the delocalization effect of conjugated molecules, the conductivity and carrier mobility of PPA-QDs films increased almost 22 times over that of OA-QD films without compromising colloidal stability and photoluminescence. PPA-QDs LEDs exhibit a maximum current efficiency of 9.08 cd A⁻¹, which is 8 times of that of OA-QDs LEDs (1.14 cd A⁻¹). This work provides critical solution for the poor conductivity of QDs in applications of energy-related devices.