LAUSR

Since 2012, when two groups reported for the first time power conversion efficiencies exceeding numbers with only one digit for metal-halide perovskite solar cells, the field has progressed rapidly. Tremendous efforts have brought a lot of advancement in the field of perovskite semiconductors and their applications in optoelectronic devices. Record efficiencies of over 24% have been reported for solar cells, but we have seen also strong developments in perovskite-based optoelectronic devices such as LEDs and photodetectors. We have now a much better understanding about this fascinating semiconductor material. Nevertheless, there are still numerous aspects to be addressed, and despite the progress in the field, we find new questions arising after answering others. This special issue on perovskite semiconductors is devoted to the next generation of optoelectronic applications. We want to summarize some important aspects concerning interface engineering, device lifetime, novel applications, and physical understanding of the processes in perovskite semiconductor applications. In this article, we will only pick selected examples to demonstrate not only the progress of the field but also the open questions and interesting research questions ahead of us.