Colloidal synthesis of halide perovskite semiconductor nanocrystals/quantum dots and their optoelectronic properties

Abstract

Halide perovskite quantum dots (QDs) have gained attention as potential materials for optoelectronics and quantum photonics applications due to their adjustable band gap, high photoluminescence quantum yield (PLQY), narrow emission, and facile synthesis. Here, we have focused on colloidal synthesis and characterization of cesium lead bromide (CsPbBr3) QDs, and optimization of reaction parameters to study and analyse their optoelectronic properties. The quantum dots were synthesized using the ligand-assisted reprecipitation (LARP) technique, employing oleylamine (OLA) and oleic acid (OA) as organic ligands to control the nucleation and growth stages of the crystal formation. Synthesis was carried out at different temperatures. We have studied the effect of varying synthesis temperature, changing reaction environment, and injection method on its optical properties. We have used characterization techniques like UV-Vis and Photoluminescence (PL) spectroscopy, and Time- Correlated Single Photon Counting (TCSPC) to analyze the absorption wavelength, fluorescence lifetime, emission wavelength, and spatially resolved photoluminescence images. We applied the Brus model, a theoretical framework, in conjunction with experimental measurements to determine the size of the synthesized nanocrystals. By optimizing the synthesis process, we obtained quantum dots with size less than 5 nm, having high photoluminescence intensity, large Stokes shift (105 nm), and excitonic lifetime (in ns) that will be suitable for LEDs and quantum emitter applications. These results showed the potential of CsPbBr3 QDs as stable, efficient, and tunable light sources for their applications and integration into photonic devices.