Amaresh Mishra (right) received his Ph.D. degree in 2000 from the Sambalpur University, India, under the coguidance of Prof. G. B. Behera and Prof. R. K. Behera, working on dye-surfactant interactions in microheterogeneous media. He started his postdoctoral research career in 1999 at the University of South Florida, Tampa, and subsequently at the University of Akron, Ohio, working with Prof. G. R. Newkome, where he gained knowledge in the area of supramolecular and dendrimer chemistry. Later, he joined the Tata Institute of Fundamental Research, Mumbai, in 2002 as a Visiting Fellow working with Prof. N. Periasamy, where he was involved in the synthesis and photophysical studies of organic light emitting materials. In 2005, he joined in the group of Prof. Peter Ba ¨uerle, University of Ulm, Germany, as an Alexander von Humboldt Fellow. His present research interests are centered on chemistry of functional oligothiophenes, donor-acceptor-based conjugated dyes, and metal complexes toward applications in solar energy conversion and molecular electronic and photonic devices. Chang-Qi Ma (left) received his bachelor's degree in chemistry from Beijing Normal University in 1998. In 2003 he obtained his Ph.D. degree at the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences in Beijing with Professor B.-W. Zhang. After that he was a postdoctoral research assistant at Heriot-Watt University in Edinburgh, U.K., with Dr. G. Cooke, until he joined the research group of Prof. P. Ba ¨uerle at the University of Ulm in 2004 as an Alexander von Humboldt fellow, where he is currently a research associate. His main research interests focus on the design and synthesis of novel π-conjugated organic materials for the application in organic electronics, e.g. organic solar cells.Peter Ba ¨uerle (center) received his Ph.D. in organic chemistry from University of Stuttgart (Germany, 1985) working with Prof. F. Effenberger. After a postdoctoral year at MIT, Boston, Massachusetts, in the group of Prof. M. S. Wrighton, he carried out independent research at the University of Stuttgart and received his habilitation (1994). After being Professor of Organic Chemistry at the University of Wu ¨rzburg (Germany, 1994-95), he became Director of the Institute for Organic Chemistry II and Advanced Materials at the University of Ulm (Germany, since 1996). Current research interests of the group include development of novel organic semiconducting and conducting materials, in particular, conjugated poly-and oligothiophenes. Synthetic strategies and new reactions for their functionalization, structure-property relationships, self-assembling properties, and applications in electronic devices, in particular organic solar cells, are investigated. Results have been published in about 200 peer-reviewed scientific papers, 3 book chapters, and 7 patents. For his work in the field of plastic electronics he was awarded with the Rene ´Descartes Prize of the European Union (2000). Guest Professorships at the University of Osaka (Japan, 2002), U...

Improving the long-term stability of perovskite solar cells is critical to the deployment of this technology. Despite the great emphasis laid on stability-related investigations, publications lack consistency in experimental procedures and parameters reported. It is therefore challenging to reproduce and compare results and thereby develop a deep understanding of degradation mechanisms. Here, we report a consensus between researchers in the field on procedures for testing perovskite solar cell stability, which are based on the International Summit on Organic Photovoltaic Stability (ISOS) protocols. We propose additional procedures to account for properties specific to PSCs such as ion redistribution under electric fields, reversible degradation and to distinguish ambient-induced degradation from other stress factors. These protocols are not intended as a replacement of the existing qualification standards, but rather they aim to unify the stability assessment and to understand failure modes. Finally, we identify key procedural information which we suggest reporting in publications to improve reproducibility and enable large data set analysis.

Manipulating the donor:acceptor (D:A) energetics, e.g. the highest occupied molecular orbital (HOMO) offset, is the key to balancing the charge separation and charge recombination for high-performance organic solar cells (OSCs)....