ENHANCEMENT OF THE STABILITY AND THE PHOTOLUMINISCENCE QUANTUM YIELD OF CESIUM LEAD HALIDE PEROVSKITES BY LIGAND DOPING

Abstract

In general, perovskites are nanoparticles having a crystalline structure. These nanoparticles attracted scientists’ attention due to their great potential in various fields ranging from chemical and industrial fields to biomedical fields. Unfortunately, cesium lead halide perovskites suffer from their high instability, where they undergo a rapid chemical decomposition within time. For this purpose, three different reaction parameters were varied starting from the time of the reaction, going to the concentration of lead bromide, and ending by the concentration of cesium oleate. Moreover, surfactant ligands were used to control the synthesis of inorganic perovskite nanoparticles. In our work, the synthesis of cesium lead halide perovskites was carried out based on the hot injection method. Henceforth, the prepared perovskites have been characterized using UV-Visible absorption spectroscopy, fluorescence spectroscopy, scanning electron microscopy, thermogravimetric analysis, and X-Ray diffraction technique. On the first hand, it was found that the most stable CsPbBr3 perovskites were formed when mixing 0.15 g (C=0.06812 M) of lead bromide heated for 40 minutes, with a volume of 1.2 mL of cesium oleate (C=0. 0092 M). Henceforward, either hexadecyltrimethylammonium Bromide (CTAB) or hexadecylpyridinium Bromide (CPB) were used as an ecofriendly surfactant to increase in the first place; the stability of the formed perovskites, and later on to boost their photoluminescence quantum yield (PLQY). Hence, the addition of CTAB had proven its efficiency on the formed CsPbBr3 nanoparticles by increasing their thermal stability and by enhancing their PLQY till 75%. Henceforth, the addition of CPB showed remarkable effects by increasing thermal stability, boosting the PLQY to 90%, preserving the crystal structure of CsPbBr3, and preventing the anion exchange between Br- and I- upon the addition of low concentrations of PbI2. On the second hand, CsPbI3 perovskites undergo rapid chemical decomposition and transformation into yellow δ-phase. Thus, it is imperative to develop a stabilized black phase for photovoltaic applications. For this purpose, a surfactant ligand was used to control the synthesis of inorganic perovskite CsPbI3 nanoparticles. Herein we demonstrate a new avenue for lead halide perovskites with the addition of either CTAB or silicon dioxide nanoparticles (SiO2 NPs) to maintain in the first place; the stability of the α-CsPbI3 phase, and later to boost their photoluminescence quantum yield (PLQY).