ISBN 9783843954655

978-3-8439-5465-5, Reihe Anorganische Chemie

Khan Lê
Electrospun Lead Halide Perovskites and Lead-free Materials for Light Emitting Devices

244 Seiten, Dissertation Universität Köln (2024), Softcover, A5

Zusammenfassung / Abstract

Lead halide perovskites gained increasing attention in light emitting application after room-temperature electroluminescence was reported in 2014. The efficiency of the devices developed to a similar level as the current state-of-the-art organic light emitting diodes used in display and lighting technologies. However, the operational stability of lead halide perovskite LEDs (PeLEDs) remains as one of the major challenges for the technology readiness of PeLEDs. Intrinsic processes such as ionic migration that leads to phase change and segregation are among the detrimental phenomena, hampering the lifetime and emission stability of PeLEDs. Possible countermeasures against migratory ions were implemented in two different ways. Lower dimensional morphology in the form of CsPbBr3 nanofibers was investigated, as the reduced degrees of freedom were expected to hinder the mobility of ions and the passivating polymeric matrix could further mitigate ionic migration. The B-site cation Pb2+ was partially replaced by Mn2+ or Zn2+ to study the size and electronic effect on optoelectronic properties, to reduce the toxic component (Pb) and possibly induce entropic stabilization. The electrospinning method was chosen for the synthesis of the perovskite/polymer composite fibers, as its upscaling potential is immensely attractive for commercialization. A proof-of-concept device with the electrospun CsPbBr3 fibers was built in this work. The promising lead-free emitters CsCu2I3 and Cs3Cu2I5 were prepared as nanofibers for the first time. Experiments for a fully fibrous PeLED, consisting of a triaxial core/intermediate/shell structure with electron- and hole- injection materials as core and shell were conducted and their characterization were performed. In summary, the results obtained in this thesis built a foundation for single-step electrospun fiber-based lead halide perovskite LEDs and fiber-based lead-free emitter LEDs.