Surface Passivation of Quantum Dot for Short-Wavelength Infrared Light Detection (conference Presentation)

Solution-processed quantum dots are promising building blocks for next-generation optoelectronic devices due to their low-cost, wide tunable bandgap and solution-processibility. Phase transfer ligand exchange has been demonstrated as a promising method to prepare small-size (diameter < 3.5 nm) PbS QDs for device fabrication. However, two obstacles limit the conventional phase transfer ligand exchange method for large-size PbS QDs: densely packed organic shells and charge-neutral (100) surfaces. In this talk, we describe a new strategy providing high-quality large size PbS QD via phase transfer ligand exchange. We use lead acetate trihydrate (PbAc2·3H2O) as a precursor reducing the steric hindrance from the densely packed organic shells, which facilitates the ligand exchange. In addition, we use methylammonium acetate (MAAc) as an additive in PbI2 ligand solution forming perovskite intermediate (MAPbI2Ac) on the (100) surface, which improves the surface passivation. The resulting photodiodes using these large-size QDs without further post-treatment exhibit a near-unity internal quantum efficiency in the short wavelength infrared region.