Sulfonated Trimethylolmelamine Ligand as a Luminescence Modulator for CsPbBr₃ Quantum Dots

Abstract

Cesium lead bromide (CsPbBr₃) quantum dots (QDs) are highly attractive for optoelectronic applications owing to their tunable band gap and strong luminescence, yet their performance is limited by surface defects and poor stability. In this work, we report the functionalization of CsPbBr₃ QDs Sulfonated Trimethylolmelamine ligands and compare their properties with conventionally capped oleic acid/oleylamine (OA/OAm) QDs. HS-QDs exhibited uniform morphology, enhanced crystallinity, and a high photoluminescence quantum yield of 91%, significantly higher than that of control QDs. Tauc plot analysis revealed a direct band gap of 2.31 ± 0.03 eV, in close agreement with literature reports, while photoluminescence spectra showed an excitonic emission at 2.41 eV, confirming efficient recombination pathways.

Light-emitting devices fabricated from HS-QDs demonstrated superior performance, achieving luminance exceeding 80,000 cd/m², external quantum efficiencies up to 20%, and improved operational stability compared to OA/OAm-based devices. HS-QD photodetectors also displayed higher responsivity and detectivity with faster response times. Moreover, HS-QDs retained optical and structural integrity under thermal and environmental stress, unlike conventional QDs which degraded rapidly.

These results highlight supramolecular ligand engineering as a powerful strategy to enhance the efficiency and long-term stability of perovskite QDs, offering new opportunities for their integration into next-generation optoelectronic devices.