Optimizing CsPbBr3 nanowires for high-performance optoelectronics: focusing on blue shift and superfast kinetics through amine-rich synthesis

Abstract

In this study, we successfully synthesized high-purity CsPbBr₃ perovskite nanocrystals (NCs) and nanowires (NWs) using a hot-injection method within an amine-rich environment, followed by a detailed analysis of their structural and optical properties. By carefully tuning the ratios of oleylamine (OAm) and octylamine (OctAm), as well as optimizing reaction temperature and time, we achieved enhanced morphology and photoluminescence characteristics of the products. The results indicate that increasing the amine content reduces the nanowire thickness and improves crystallinity, yielding NWs with an approximate diameter of 3 nm and NCs with a uniform size distribution of 9.7 ± 0.2 nm. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) confirmed that the CsPbBr₃ nanostructures exhibit a pure orthorhombic phase. Photoluminescence (PL) and UV-vis absorption analyses revealed narrow emission peaks at 520 nm and 465 nm for NCs and NWs, respectively, with the NWs showing a pronounced blue shift and a primary exciton absorption peak at 450 nm, indicating a strong quantum confinement effect. Time-resolved photoluminescence spectroscopy (TRPL) measurements showed an average exciton lifetime of 15.29 ns for NWs, which is notably longer than the 10.55 ns observed for NCs. Femtosecond transient absorption spectroscopy (fs-TA) further demonstrated significant differences in ground-state bleach (GSB) dynamics between the nanostructures, with NWs reaching peak bleach at 9.32 ps compared to 6.16 ps for NCs. These findings highlight the slower carrier recombination rate in NWs, which enhances quantum confinement effects. This work provides both theoretical and experimental insights into the potential application of one-dimensional perovskite nanostructures in high-efficiency optoelectronic devices.