Microwave-Mediated Synthesis of Lead-Free Cesium Titanium Bromide Double Perovskite: A Sustainable Approach

Abstract

Theoretical studies have identified cesium titanium bromide (Cs2TiBr6), a vacancy-ordered double perovskite, as a promising lead-free and earth-abundant candidate to replace Pb-based perovskites in photovoltaics. Our research is focused on overcoming the limitations associated with the current Cs2TiBr6 syntheses, which often involve high-vacuum and high-temperature evaporation techniques, high-energy milling, or intricate multistep solution processes conducted under an inert atmosphere, constraints that hinder industrial scalability. This study presents a straightforward, low-energy, and scalable solution procedure using microwave radiation to induce the formation of highly crystalline Cs2TiBr6 in a polar solvent. This methodology, where the choice of the solvent plays a crucial role, not only reduces the energy costs associated with perovskite production but also imparts exceptional stability to the resulting solid, in comparison with previous reports. This is a critical prerequisite for any technological advancement. The low-defective material demonstrates unprecedented structural stability under various stimuli such as moisture, oxygen, elevated temperatures (over 130 °C), and continuous exposure to white light illumination. In summary, our study represents an important step forward in the efficient and cost-effective synthesis of Cs2TiBr6, offering a compelling solution for the development of eco-friendly, earth-abundant Pb-free perovskite materials.

Improving the Photoelectric Conversion Efficiency of Cs2TiBr6-Based Perovskite Solar Cells Using a Theoretical Simulation Method

“…Recent investigations suggest that controlling the aqueous solution can also enhance environmental stability. For instance, Julián-López et al induced the formation of highly crystalline Cs 2 TiBr 6 using microwave radiation in polar solvents, not only reducing energy costs associated with perovskite production but also imparting exceptional stability to the resulting Cs 2 TiBr 6 . Konstantatos et al further enhanced Cs 2 TiBr 6 perovskite stability by post-treating it with SnBr 4 , adjusting the amount and reaction conditions to achieve optimal stability.…”

Intrinsic Defects of Vacancy-Ordered Perovskite Cs2TiIBr5 for Solar Cells

“…Relatively little research has been done on vacancy-ordered perovskites for solar cells. Studies have shown that Cs 2 TiX 6 (X = Br and I) possesses multiple desirable attributes including good stability and high optical absorption coefficients in the visible light ranges. − More recently, Zhao et al and Reyes-Francis et al, respectively, pointed out the ease of synthesis and high power conversion efficiency (PCE) of Cs 2 TiX 6 . , The impact of large exciton binding energy in Cs 2 TiX 6 may potentially be mitigated through atomic substitution or by changing the dielectric environment of the insulating organic layer. − The aforementioned discussions suggest that Cs 2 TiX 6 holds the potential for use in solar cells. However, existing calculations and experiments have proven that both Cs 2 TiBr 6 and Cs 2 TiI 6 have some shortcomings that limit their further applications. , First, these two materials have quasi-direct bandgaps with indirect bandgaps between Γ (valence band maximum, VBM) and X (conduction band minimum, CBM), which are detrimental to their photovoltaic performance .…”