Towards Extending Solar Cell Lifetimes: Addition of a Fluorous Cation to Triple Cation-Based Perovskite Films

Special Issue: Perovskite OptoelectronicsOrganohalide perovskites have emerged as highly promising replacements for thin-film solar cells. However, their poor stability under ambient conditions remains problematic, hindering commercial exploitation. The addition of a fluorous-functionalized imidazolium cation during the preparation of a highly stable cesium-based mixed perovskite material Cs(MAFA)Pb(IBr) (MA=methylammonium; FA=formamidinium) has been shown to influence its stability. The resulting materials, which vary according to the amount of the fluorous-functionalized imidazolium cation present during fabrication, display a prolonged tolerance to atmospheric humidity (>100 days) along with power conversion efficiencies exceeding 16 %. This work provides a general route that can be implemented in a variety of perovskites and highlights a promising way to increase perovskite solar cell stability.M.A.F. acknowledged financial support from the CSIC (PIE‐201760E002)

Advances in 4D Printing of Shape-Memory Materials: Current Status and Developments

The next generation 3D printing is now termed as four-dimensional (4D) printing technology that involves the printing of complex geometries with smart materials. The rise of 4D technological developments leads to finding modern production techniques and new materials. Under this context, 4D printing of shape-memory alloys (SMAs), shape-memory polymers (SMPs), and composites have opened up the possibility of systems for self-assembly, self-healing, and changes in material properties. The development in shape-memory materials, their deformation mechanisms, and mathematical modeling has promoted the research area of 4D printing. The present chapter covers a detailed discussion of various 3D- and 4D-printing additive manufacturing techniques. The shape-memory mechanism of SMAs and SMPs along with recent advancements in 4D printing is screened. The chapter also presents the challenging aspect in 4D printing of SMAs/SMPs and its application in various fields. Further, in outlook we have also briefed the materials, physics, and technologies covered in different chapters of the book.Scopu