Abstract
The photoluminescence (PL), color purity, and stability of lead halide perovskite nanocrystals depend critically on surface passivation. We present a study on the temperature-dependent PL and PL decay dynamics of lead bromide perovskite nanocrystals characterized by different types of A cations, surface ligands, and nanocrystal sizes. Throughout, we observe a single emission peak from cryogenic to ambient temperature. The PL decay dynamics are dominated by surface passivation, and a postsynthesis ligand exchange with a quaternary ammonium bromide (QAB) results in more stable passivation over a larger temperature range. The PL intensity is highest from 50 to 250 K, which indicates that ligand binding competes with the thermal energy at ambient temperature. Despite the favorable PL dynamics of nanocrystals passivated with QAB ligands (monoexponential PL decay over a large temperature range, increased PL intensity and stability), surface passivation still needs to be improved to achieve maximum emission intensity in nanocrystal films.
Highlights
The photoluminescence (PL), color purity, and stability of lead halide perovskite nanocrystals depend critically on surface passivation
It has been well established that the composition and nature of the NC surface strongly influence their optical properties.[1−3] Recently, lead halide perovskite NCs (LHP NCs), with an APbX3 composition, have emerged as a promising material due to their ease of preparation, broadly tunable band gap, high photoluminescence quantum yield (PLQY), and excellent color purity.[4−8] This remarkable set of properties makes them ideal candidates for light emission technologies, such as light-emitting diodes, lasers, and single-photon emitters.[9−11]
PL spectroscopy at cryogenic temperatures has been used to investigate the temperature-dependent excitonic properties of traditional semiconductors and recently of LHP NCs.[12−14] In this respect, there has been some disagreement in the literature about whether LHP NCs undergo temperature-induced phase transitions from room temperature to cryogenic temperatures, whether the emission at cryogenic temperatures consists of a single peak or multiple peaks,[15−20] and, in the latter case, on the exact origin of these multiple peaks
Summary
The photoluminescence (PL), color purity, and stability of lead halide perovskite nanocrystals depend critically on surface passivation. We study the photoluminescence properties of APbBr3 (A = Cs, MA, or FA) NCs with respect to temperature, NC size, and surface passivating ligands and observe the following.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
