Systematic optimization of metal salt-based ligand exchange for high-efficiency quantum dot light-emitting diodes

초록

This study systematically investigates the effects of metal salt-based inorganic ligand exchange on quantum dot light-emitting diode (QLED) performance. Ligand exchange using Zn(NO3)2 center dot xH2O effectively replaced long-chain organic ligands on quantum dot surfaces, significantly enhancing surface passivation and improving charge transport. X-ray photoelectron spectroscopy confirmed the successful incorporation of Zn2+ ions and increased surface-bound nitrate species, validating effective ligand exchange. Atomic force microscopy (AFM) revealed optimal surface smoothness at a Zn(NO3)2 center dot xH2O concentration of 0.02 M, correlating with enhanced photoluminescence intensity due to reduced non-radiative recombination. Device performance tests confirmed significant improvements: the QLED treated with 0.02 M Zn(NO3)2 center dot xH2O demonstrated a 38 % enhancement in current efficiency compared to the untreated device. Additionally, post-annealing at 120 degrees C further increased current efficiency by approximately 7 % relative to the non-annealed sample. These optimized ligand exchange and annealing strategies provide valuable insights for the advancement and commercialization of high-efficiency QLED technologies.

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