Organic–inorganic hybrid perovskite quantum dots with high PLQY and enhanced carrier mobility through crystallinity control by solvent engineering and solid-state ligand exchange

Abstract

The photoluminescence quantum yield (PLQY) and charge carrier mobility of organic-inorganic perovskite QDs were enhanced by the optimization of crystallinity and surface passivation as well as solid-state ligand exchange. The crystallinity of perovskite QDs was determined by the Effective solvent field (Esol) of various solvents for precipitation. The solvent with high Esol could more quickly countervail the localized field generated by the polar solvent, and it causes fast crystallization of the dissolved precursor, which results in poor crystallinity. The post-ligand adding process (PLAP) and post-ligand exchange process (PLEP) increase the PLQY of perovskite QDs by reducing non-radiative recombination and the density of surface defect states through surface passivation. Particularly, the post ligand exchange process (PLEP) in the solid-state improved the charge carrier mobility of perovskite QDs in addition to the PLQY enhancement. The ligand exchange with short alkyl chain length ligands could improve the packing density of perovskite QDs in films by reducing the inter-particle distance between perovskite QDs. The maximum hole mobility of 6.2 × 10-3 cm2 V-1 s-1, one order higher than that of pristine QDs without the PLEP, is obtained at perovskite QDs with hexyl ligands. By using PLEP treatment, compared to the pristine device, a 2.5 times higher current efficiency in perovskite QD-LEDs was achieved due to the improved charge carrier mobility and PLQY.

Water-Assisted Perovskite Quantum Dots with High Optical Properties

“…Figure 5b and S4b showed the normalized PL spectra of the MAPbBr3 PeQDs. The PL spectra of the prepared MAPbBr3 PeQDs corresponded to the previously reported ones with cubic structures [26]. The PL peak of MAPbBr3 PeQDs was red shifted from 522 nm to 526 nm by assisting with water and had a narrower FWHM compared with that of the MAPbBr3 without water (Table 1).…”

Quantifying Capacitive and Diffusion-Controlled Charge Storage from 3D Bulk to 2D Layered Halide Perovskite-Based Porous Electrodes for Efficient Supercapacitor Applications

“…Hybrid halide perovskites (HHPs) are the materials of the decade as tremendous progress in perovskite solar cells, 1−4 perovskite light-emitting diodes, 5−9 perovskite-based detectors, and memristor applications has been observed owing to their superior optoelectronic properties such as high carrier mobility, 10,11 high absorption coefficient, 10,12 ambipolar charge transport, 13,14 high quantum yield, 15,16 high color purity, excellent defect tolerance with low-temperature solution −processing, and tunable emission over a broad spectrum. 17 Due to the mixed electronic−ionic conductivity, hybrid perovskites have also attracted attention toward energy storage applications.…”

Efficient Quantum Dot Light-Emitting Diodes Based on Trioctylphosphine Oxide-Passivated Organometallic Halide Perovskites

“…Additionally, ligand-exchange methods were also used to enhance the PL performances of perovskites. 31,42 Unfortunately, the above-reported methods have been rarely applied in organic–inorganic hybrid perovskite-based electroluminescent (EL) devices due to the limited conductivity of perovskite QDs after treatment. In addition, researchers have also used tetraethyl orthosilicate, tetramethyl orthosilicate, and (3-aminopropyl) triethoxysilane to synthesize silica-coated perovskite NPs, 43−45 but the shell thickness has a notable influence on device performances due to the insulative characteristics of silica.…”