Dear Colleagues,

  Since the two decades, researchers have been working on halide perovskites, a family of materials with excellent performance and cheap production prices in solar cells. Perovskite solar cells have made remarkable achievements in recent years, with efficiency increasing rapidly from around 3% in 2009 to more than 29.1% today. However, a device's efficiency is not everything. To ensure long-term safety and to avoid toxicity, lead-free perovskite materials have become a higher priority for commercialization. Still, there remains a challenge in making stable lead-free perovskite solar cells.

  In this special issue of Applied Chemical Engineering, we plan to presents a collection of theoretical and experimental papers that reflect on the most recent advances in the field. We are particularly interested in articles that describe novel approaches to improving the efficiency and stability of perovskite solar cells which are compatible with existing technologies. We hope that lead-free perovskites solar cells will be soon widespread in everybody’s life, making a step forward in the renewable energy.

Dr. Tushar Dhabal Das