Sequential Co‐Passivation in InAs Colloidal Quantum Dot Solids Enables Efficient Near‐Infrared Photodetectors

Abstract

III‐V colloidal quantum dots (CQDs) are promising materials for optoelectronic applications, for they avoid heavy metals while achieving absorption spanning the visible to the infrared (IR). However, the covalent nature of III‐V CQDs requires the development of new passivation strategies to fabricate conductive CQD solids for optoelectronics: this work shows herein that ligand exchanges, previously developed in II‐VI and IV‐VI quantum dots and employing a single ligand, do not fully passivate CQDs, and that this curtails device efficiency. Guided by density functional theory (DFT) simulations, this work develops a co‐passivation strategy to fabricate indium arsenide CQD photodetectors, an approach that employs the combination of X‐type methyl ammonium acetate (MaAc) and Z‐type ligands InBr3. This approach maintains charge carrier mobility and improves passivation, seen in a 25% decrease in Stokes shift, a fourfold reduction in the rate of first‐exciton absorption linewidth broadening over time‐under‐stress, and leads to a doubling in photoluminescence (PL) lifetime. The resulting devices show 37% external quantum efficiency (EQE) at 950 nm, the highest value reported for InAs CQD photodetectors.

Gate Voltage Adjusting PbS‐I Quantum‐Dot‐Sensitized InGaZnO Hybrid Phototransistor with High‐Sensitivity

“…The dynamics were fit to biexponential curves with two decay components of 100-ps scale (𝜏 1 ) and 1-ns scale (𝜏 2 , Table S2, Supporting Information). [39] The faster and significant decay (𝜏 1 , 170 ps vs 195 ps) once again demonstrate the ultrafast electron-transfer between the PbS-I film and the a-IGZO layer at zero bias, while the order of carrier transfer rate is ≈100 ps. Furthermore, the extended lifetimes (𝜏 2 , 1780 ps vs 1580 ps) are mainly attributed to the suppression of recombination by the spatial separation of photo-generated carriers, [40] which is consistent with the conclusion of the PL spectroscopy tests, thus again providing a theoretical basis for the aforementioned working mechanism (Figure 3a).…”

Colloidal quantum dot materials for next-generation near-infrared optoelectronics

“…11b). Additionally, InAs CQD ink 130 and HgTe CQD ink 128 are also highly attractive to fabricate high-quality optoelectronic devices.…”

Interface defects repair of core/shell quantum dots through halide ion penetration

“…18–23 Achieving precise control over trap states in core–shell QDs remains a formidable challenge, yet addressing it would lead to significant advancements in their diverse applications. 24–26…”