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.

Perovskite Solar Cells (PSCs) have attracted considerable attention because of their unique features and high efficiency. However, the stability of perovskite solar cells remains to be improved. In this study, we modified the TiO ${}_{\mathrm{2}}$ Electron Transport Layer (ETL) interface with PbCl ${}_{\mathrm{2}}$. The efficiency of the perovskite solar cells with carbon electrodes increased from 11.28% to 13.34%, and their stability obviously improved. The addition of PbCl ${}_{\mathrm{2}}$ had no effect on the morphology, crystal structure, and absorption property of the perovskite absorber layer. However, it affected the band energy level alignment of the solar cells and accelerated the electron extraction and transfer at the interface between the perovskite layer and the ETL, thus enhancing the overall photovoltaic performance. The interfacial modification of ETL with PbCl ${}_{\mathrm{2}}$ is a promising way for the potential commercialization of low-cost carbon electrode-based perovskite solar cells.