Charge carrier dynamics in Cs<sub>1-x</sub>FA<sub>x</sub>PbI<sub>3</sub> perovskite quantum dots : A nanosecond transient absorption spectroscopy analysis
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초록
내용
Among various colloidal perovskite quantum dots (PQDs), Cs1-xFAxPbI3 can adjust the absorption band depending on the A-site cation composition. Organic FA cations can control the bandgap, photoluminescence (PL), and charge transfer (CT) properties to improve device performance in optoelectronic applications. In particular, the excited state of PQDs is investigated by transient absorption spectroscopy (TAS), and understanding the photophysics and charge carrier dynamics is important to achieve efficient light-to-power conversion in energetic materials and devices. In the obtained transient absorption spectra of all examined PQD films, a noticeable photo-induced absorption (PIA) signal at 500 nm, coupled with a ground-state bleaching (GSB) signal ranging from 685 to 745 nm, is observed. The progressive elevation of formamidinium (FA) content within the PQDs results in faster non-radiative recombination, indicating a decreased density of trap states.