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.

In recent years, Perovskite Light-Emitting Diodes (PeLEDs) have received considerable attention in academia. However, with the development of PeLEDs, commercial applications of full-color PeLED technology are largely limited by the progress of blue-emitting devices, due to the uncontrollably accurate composition, unstable properties, and low luminance. In this article, we add Cesium chloride (CsCl) to the quasi-two-dimensional (quasi-2D) perovskite precursor solution and achieve the relatively blue shifts of PeLED emission peak by introducing chloride ions for photoluminescence (PL) and electroluminescence (EL). We also found that the introduction of chlorine ions can make quasi-2D perovskite films thinner with smoother surface of 0.408 nm. It is interesting that the EL peaks and intensities of PeLED are adjustable under different driving voltages in high concentration chlorine-added perovskite devices, and different processes of photo-excited, photo-quenched, and photo-excited occur sequentially with the increasing driving voltage. Our work provides a path for demonstrating full-color screens in the future.