Photo-/electro-luminescence Enhancement of CsPbX3 (X = Cl, Br, or I) Perovskite Quantum Dots via Thiocyanate Surface Modification

All-inorganic lead halide perovskite quantum dots (PQDs) are among the most highly applicable luminescent materials for wide-color-gamut displays. Since the development of all-inorganic PQDs, several methods have been implemented to enhance their photo-luminescent quantum yield (PLQY) and stability. However, most treatment procedures only focus on optimizing the green CsPbBr3 perovskite quantum dots. In this work, we extended the usage of SCN− ligands to modify the surface of blue, green, and red PQDs for improving their luminescence properties. The presence of SCN− on the surface of PQDs was confirmed via Fourier-transform infrared spectroscopy and energy-dispersive X-ray spectroscopy. On the basis of the X-ray photoelectron spectra, the surface modification of PQDs enhanced the PL intensity and PLQY due to the removal of Pb2+ surface defects. The modified PQDs were applied to quantum dot light-emitting diodes (QLEDs), and the performance of the devices was satisfactory, thereby indicating their potential applications in high-quality displays.