Colloidal InAs Quantum Dot‐Based Infrared Optoelectronics Enabled by Universal Dual‐Ligand Passivation

Abstract

Solution‐processed low‐bandgap semiconductors are crucial to next‐generation infrared (IR) detection for various applications, such as autonomous driving, virtual reality, recognitions, and quantum communications. In particular, III–V group colloidal quantum dots (CQDs) are interesting as nontoxic bandgap‐tunable materials and suitable for IR absorbers; however, the device performance is still lower than that of Pb‐based devices. Herein, a universal surface‐passivation method of InAs CQDs enabled by intermediate phase transfer (IPT), a preliminary process that exchanges native ligands with aromatic ligands on the CQD surface is presented. IPT yields highly stable CQD ink. In particular, desirable surface ligands with various reactivities can be obtained by dispersing them in green solvents. Furthermore, CQD near‐infrared (NIR) photodetectors are demonstrated using solution processes. Careful surface ligand control via IPT is revealed that enables the modulation of surface‐mediated photomultiplication, resulting in a notable gain control up to ≈10 with a fast rise/fall response time (≈12/36 ns). Considering the figure of merit (FOM), EQE versus response time (or −3 dB bandwidth), the optimal CQD photodiode yields one of the highest FOMs among all previously reported solution‐processed nontoxic semiconductors comprising organics, perovskites, and CQDs in the NIR wavelength range.

Low-Temperature Annealing of Inkjet-Printed CsPbBr3 Perovskite Nanocrystal Film for Light-Emitting Diodes

“…Metal halide perovskite materials, such as bulk film, quasi-two-dimensional (quasi-2D), nanocrystals (NCs), have garnered significant attention as promising candidates for solution-processed light-emitting diodes (LEDs) owing to their exceptional photoluminescence quantum yield (PLQY) and excellent color purity across the visible-to-near-infrared spectrum. − Inkjet printing has emerged as a promising solution process for fabricating quantum dot (QD)-based optoelectrical optoelectronic and perovskite NC-LEDs, and quasi-2D perovskite LEDs due to the small-pixel size and on-demand patterning without mask-free techniques, crucial for the display application. − This method allows for film deposition using significantly less ink compared to the spin-coating process, leading to cost reduction and an environmentally friendly process. − Inkjet-printed quasi-2D perovskite LEDs have been fabricated using metal halide precursor solutions. ,− Precursor solutions comprise metal halide and ammonium halide spacer cations dissolved in a polar solvent such as dimethyl sulfoxide (DMSO). The metal halide precursor solutions are converted to quasi-2D perovskite film during solvent evaporation after the annealing process.…”