Toward Efficient Perovskite Solar Cells: Progress, Strategies, and Perspectives

Since the first publication by Miyasaka in 2009 on the use of lead halide perovskite as a light-harvesting material (Kojima, A.; Teshima, K.; Shirai, Y.; Miyasaka, T. Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells. J. Am. Chem. Soc. 2009, 131, 6050), unprecedented successes have been achieved and great efforts have been made in the field of perovskite solar cells (PSCs) to push the power conversion efficiency (PCE) past 25%, which corresponds to ∼80% of this material's theoretical bandgap limit determined on the basis of the Shockley–Queisser theory. Recent progress is mainly attributed to the development of key strategies that effectively reduce the defects on the surface of the perovskite layer and minimize non-radiative recombination at the interfaces, thereby enhancing device efficiency. For future development of PSCs with PCEs exceeding 26%, this Perspective highlights an investigation of the key factors that have allowed realization of efficient PSCs with state-of-the-art PCEs and includes a discussion of practical strategies, including full optimization of the electron-transport layer, minimization of defect loss related to non-radiative recombination, and enhancement of light-harvesting near the band-edge.