This supplementary material provides detailed experimental data and analysis for the study on enhancing the performance of deep-blue perovskite light-emitting diodes (PeLEDs) by incorporating sulfonate ligands. The key findings include: 1. **Bonding and Incorporation of Sulfonate Ligands**: - X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR) confirm the successful bonding and incorporation of ethanesulfonate and propanesulfonate ligands into the perovskite structure. - X-ray diffraction (XRD) patterns show that the sulfonate ligands do not alter the cubic phase of the perovskite. 2. **Absorption and Morphological Properties**: - UV-visible absorption spectra and Tauc plots indicate that the sulfonate ligands do not induce the formation of 2D structures. - Scanning electron microscopy (SEM) images show a significant decrease in grain size from 300 nm to 120 nm, likely due to the presence of sulfonate ligands. 3. **Photoluminescence Properties**: - Power-dependent photoluminescence analysis and photoluminescence quantum efficiency (PLQY) measurements show that optimal PLQY values are achieved at specific ratios of sulfonate ligands to Pb(II), with higher PLQY values observed for longer carbon chains. 4. **Electrical and Spectral Stability**: - Current density-voltage (J-V) curves and electroluminescence (EL) spectra demonstrate the operational stability and spectral stability of the PeLEDs. - Despite slightly higher surface roughness and lower charge carrier mobilities, ESP- and PSP-based LEDs achieve higher external quantum efficiencies (EQE) compared to methanesulfonate-treated perovskite (MSP) films. 5. **Operational Lifespan**: - Operational lifetimes and EL spectra over time show that PSP-based LEDs have a longer operational lifespan and better spectral stability under high brightness conditions. Overall, the study highlights the potential of sulfonate ligands in improving the performance and stability of deep-blue perovskite PeLEDs, aligning with the Rec. 2020 standards.This supplementary material provides detailed experimental data and analysis for the study on enhancing the performance of deep-blue perovskite light-emitting diodes (PeLEDs) by incorporating sulfonate ligands. The key findings include: 1. **Bonding and Incorporation of Sulfonate Ligands**: - X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR) confirm the successful bonding and incorporation of ethanesulfonate and propanesulfonate ligands into the perovskite structure. - X-ray diffraction (XRD) patterns show that the sulfonate ligands do not alter the cubic phase of the perovskite. 2. **Absorption and Morphological Properties**: - UV-visible absorption spectra and Tauc plots indicate that the sulfonate ligands do not induce the formation of 2D structures. - Scanning electron microscopy (SEM) images show a significant decrease in grain size from 300 nm to 120 nm, likely due to the presence of sulfonate ligands. 3. **Photoluminescence Properties**: - Power-dependent photoluminescence analysis and photoluminescence quantum efficiency (PLQY) measurements show that optimal PLQY values are achieved at specific ratios of sulfonate ligands to Pb(II), with higher PLQY values observed for longer carbon chains. 4. **Electrical and Spectral Stability**: - Current density-voltage (J-V) curves and electroluminescence (EL) spectra demonstrate the operational stability and spectral stability of the PeLEDs. - Despite slightly higher surface roughness and lower charge carrier mobilities, ESP- and PSP-based LEDs achieve higher external quantum efficiencies (EQE) compared to methanesulfonate-treated perovskite (MSP) films. 5. **Operational Lifespan**: - Operational lifetimes and EL spectra over time show that PSP-based LEDs have a longer operational lifespan and better spectral stability under high brightness conditions. Overall, the study highlights the potential of sulfonate ligands in improving the performance and stability of deep-blue perovskite PeLEDs, aligning with the Rec. 2020 standards.