Self-Stabilized Quasi-2D Perovskite with an Ion-Migration-Inhibition Ligand for Pure Green LEDs

Perovskite light-emitting diodes (PeLEDs) have recently achieved a great breakthrough in external quantum efficiency (EQE). However, the operational stability of pure primary color PeLEDs lags far behind because of serious ion migration. Herein, a self-stabilized quasi-2D perovskite is constructed with a strategically synthesized ion-migration-inhibition ligand (IMIligand) to realize highly stable and efficient pure green PeLEDs approaching the standard green light of Rec. 2020. The IMIligand takes the role to not only eliminate migration pathways and anchor halide ions to suppress the ion migration but to also further enhance the crystalline orientation and energy transfer in quasi-2D perovskites. Meanwhile, the self-stabilized quasi-2D perovskite overcomes the degradation of electrical performance caused by conventional exogenous passivation additives. Ultimately, the figure of merit of the pure green quasi-2D PeLEDs is at least double that of previous works. The devices achieve an EQE of 26.2% and operational stability of 920 min at initial luminance of 1000 cd m–2

Balancing Charge Injection via a Tailor-Made Electron-Transporting Material for High Performance Blue Perovskite QLEDs

One of the great challenges in perovskite quantum dot light-emitting diodes (Pe-QLEDs) is the unbalanced charge injection that significantly hinders the device performance and stability. Herein, we tailor-made a high mobility electron-transporting material (ETM), named B2, to balance the carrier injection in blue Pe-QLEDs. B2 with a tailored asymmetric anthracenyl structure exhibits a promising electron mobility of 2.7 × 10–4 cm2·V–1·s–1, which is almost 20 times higher than the commonly used ETM-TPBi (1.1 × 10–5 cm2·V–1·s–1). Subsequently, sky blue (490 nm) Pe-QLED with B2 as the ETM presented a remarkably high external quantum efficiency (EQE) of 13.17% and a low turn-on voltage of 2.2 V, which is much better than that of the TPBi-based device (EQE of 8.31% and Vturn‑on of 3.2 V). In addition, B2 also demonstrated a universal application in green and deep blue Pe-QLEDs. This work provides an important guidance to rational design of high electron mobility ETMs for high-performance LEDs