Brightness and Lifetime Improved Light-Emitting Diodes from Sr-Doped Quasi-Two-Dimensional Perovskite Layers

Green Perovskite Light-Emitting Diodes (PeLEDs) have attracted wide attention for full spectrum displays. However, the inferior film morphology and luminescence property of quasi-two-dimensional (quasi-2D) perovskite layers limit the photoelectric property of the PeLEDs. In this paper, the effect of strontium (Sr) doped in quasi-2D perovskite layers is investigated to obtain a high-quality active layer. The morphologies and optical properties of Sr-doped quasi-2D perovskite films with different concentrations are studied. With the addition of strontium, more low-dimensional-layer perovskite phases ( $n\mathrm{=}\mathrm{2}$ and $n\mathrm{=}\mathrm{3}$) appear in quasi-2D perovskite films, providing efficient intraband carrier funneling pathway and facilitating radiative recombination. The photoluminescence (PL) peak intensity of optimized Sr-doped quasi-2D perovskite layers increases 50% compared with the non-strontium counterpart. Moreover, green PeLEDs based on a Sr-doped quasi-2D perovskite layer reach a maximum luminance ( $L_{\max }$) of 2943.77 cd/m ${}^{\mathrm{2}}$, which is three times of the control device. The electroluminescence (EL) peaks of Maximum External Quantum Efficiency (MEQE) and $L_{\max }$ of Sr-doped PeLEDs exhibite a slight shift, indicating the excellent stability and performance of Sr-doped devices. The optimized device can continuously operate for 360 s at MEQE driving voltage, resulting in a half-lifetime of $\mathrm{\sim }$60 s, which is 3-fold greater than that of the control PeLEDs.