Multifunctional Short-Chain 2-Thiophenealkylammonium Bromide Ligand-Assisted Perovskite Quantum Dots for Efficient Light-Emitting Diodes

Lead halide perovskite quantum dots (QDs) have attractedgreatinterest for application in light-emitting diodes (LEDs) due to theirhigh photoluminescence quantum yield (PLQY), solution processability,and high color purity, showing great potential for next-generationfull-color display and lighting technologies. Conventional long-chaininsulating oleic acid (OA)/oleamine (OAm) ligands exhibit dynamicbinding to the surface of QDs, resulting in a plethora of extra surfacedefects and inferior optoelectronic properties. Herein, a sole multifunctionalligand with optimized carbon chain length, that is, 2-thiophenepropylaminebromide (ThPABr), was creatively designed and introduced into CsPbBr3 QDs, which not only replaces OAm and provides a bromine sourcebut also coordinates with the uncoordinated surface Pb2+ of QDs through the thiophene, passivating surface defects and increasingthe PLQY of the film to 83%. More importantly, the interaction betweenthe electron donor-thiophene ring and QDs can enhance electroninjection and improve carrier balance. The resulting green LED exhibitedsignificant performance improvement, showing ultrahigh spectral stabilityunder high operating voltage, achieving a maximum external quantumefficiency of 10.5%, and extending the operating lifetime to 5-foldthat of the reference. Designing a single multifunctional ligand presentsa promising and convenient strategy for selecting surface ligandsthat can enhance the performance of LEDs or other optoelectronic devices.

Automated summary

By using 2-thiophenepropylamine bromide (ThPABr) as a multifunctional ligand in CsPbBr3 quantum dots, the film's photoluminescence quantum yield (PLQY) was increased to 83%, and the green LED exhibited significant performance improvement, including ultrahigh spectral stability, a maximum external quantum efficiency of 10.5%, and an extended operating lifetime that is 5 times longer than the reference sample.