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Long-term operational stability remains a major challenge in the commercialization of perovskite solar cells (PSCs). While the major thrust of recent research effort has been on understanding the degradation mechanism, many new approaches are being explored to improve the performance stability of PSCs. In this issue are four Letters that discuss new strategies to achieve stabilization of PSCs. Editorial Advisory Board members highlight these new advances herein.

Low toxicity and an ideal energy bandgap make two-dimensional (2D) Ruddlesden–Popper tin-based halide perovskites a promising photovoltaic material. However, the disordered crystal orientation and the oxidation of Sn2+ to Sn4+ still need to be addressed. Here, we demonstrate that the annealing of FASnI3 assisted by phenyl ethylammonium chloride enables the formation of more ordered 2D tin-based perovskite crystals oriented vertically. We use in situ synchrotron-based grazing incident X-ray diffraction to correlate the higher crystal orientation to the better device performance. We measured a maximum power conversion efficiency of more than 9%. Furthermore, we demonstrate that the phenyl ethylammonium chloride acts as a barrier layer at the surface of the crystals protecting the tin from the oxidation. Hence, this work paves the way for more efficient and stable lead-free perovskite solar cells.

As metal halide solar cells reach photoconversion efficiencies over 25%, one question that is often being asked is, “What is next?” Interestingly, there are plenty of new opportunities to explore in the perovskite world. The four articles selected for the Energy Spotlight in this issue are just a few examples to show the dynamic nature of metal halide perovskite research. New inroads are being made to explore new heterostructures and luminescent semiconductor nanoclusters, understand phase stability, and offer new insights into excited state processes. Such advances provide new avenues to further expand the scope of perovskite research, offering new areas to explore.