Methylammonium Lead Iodide Perovskite Quantum Dots Optical Performance and Stability Challenges

The perovskite quantum dots of methylammonium lead iodide (MAPbI<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>) have got a lot of interest as potential materials that may be utilized in the optoelectronic equipment with their impressive optical characteristics, such as adjustable emission colours and a high photoluminescence quantum yield. MAPbI<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> perovskite QDs were made using ligand-assisted reprecipitation (LARP) in chloroform in this work. The optical properties and long-term stability were determined between the synthesis conditions of various precursor volumes (5, 10, 15, and 20 μL) to determine how these factors influenced the optical properties and stability. Optical characterization identified that the 10 μL precursor addition gave rise to QDs with maximum photoluminescence quantum efficiency of 1.26 x 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> with a close second place to the 5 μL sample (1.24 x 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup>). On the contrary, the quantum efficiencies of the 15 μL and 20 μL samples were much lower at 6.10 x 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> and 5.74 x 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> respectively, even though the quantum dot concentrations in the samples were higher. Nevertheless, a five-week study on stability showed an anti-correlation between quantum efficiency and environmental stability. Photoluminescence decay of the 10 μL sample was 51% with the more sensitive 20 μL sample decaying by 69% of its original intensity, a loss of 31% only. This trade-off between optical performance and stability shows the extreme needs of optimization of perovskite QDs based on methylammonium. The high rate at which all the samples degraded is ascribed to moisture, ion movement, photo-oxidation, and volatility of methylammonium cation. These results show that further developments in stabilization methods, such as compositional engineering, core-shell topologies, and advanced encapsulation strategy are required to allow the practical use of MAPbI<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> perovskite QDs in optoelectrical applications.

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