Highly efficient pure red light-emitting diodes enabled by multifunctional ligand-coordinated CsPbI3 quantum dots

Abstract

Efficient perovskite light-emitting diodes (PeLEDs) that emit at wavelengths between 620 and 650 nm are key to the next generation of ultrahigh-definition displays. Quantum-confined CsPbI₃ quantum dots (QDs) can overcome the intrinsically narrow bandgap, thus meeting the requirements of pure red emitters. However, the inherent instability and poor carrier transport properties of CsPbI₃ QDs hinder their device performance. Herein, we introduce thiophene-2-sulfonamide (2-ThSA), a short-chain multifunctional ligand, to passivate surface defects and enhance carrier transport in CsPbI₃ QDs. The 2-ThSA treated QDs exhibited a near 100 % photoluminescence quantum yield (PLQY), observably improved stability, and enhanced carrier transport properties due to the strong interactions between the CsPbI₃ QDs and multiple functional groups of 2-ThSA. PeLEDs based on these modified QDs demonstrated superior spectral stability, reached a remarkable external quantum efficiency (EQE) of 28.73 %, and displayed low efficiency roll-off. Additionally, large-area devices (64 mm²) showed an EQE exceeding 20 %, highlighting the potential of our approach for high-performance, large-scale displays.