Degradation mechanism of hybrid tin-based perovskite solar cells and the critical role of tin (IV) iodide

Tin perovskites have emerged as promising alternatives to toxic lead perovskites in next-generation photovoltaics, but their poor environmental stability remains an obstacle towards more competitive performances. Therefore, a full understanding of their decomposition processes is needed to address these stability issues. Herein, we elucidate the degradation mechanism of 2D/3D tin perovskite films based on (PEA)0.2(FA)0.8SnI3 (where PEA is phenylethylammonium and FA is formamidinium). We show that SnI4, a product of the oxygen-induced degradation of tin perovskite, quickly evolves into iodine via the combined action of moisture and oxygen. We identify iodine as a highly aggressive species that can further oxidise the perovskite to more SnI4, establishing a cyclic degradation mechanism. Perovskite stability is then observed to strongly depend on the hole transport layer chosen as the substrate, which is exploited to tackle film degradation. These key insights will enable the future design and optimisation of stable tin-based perovskite optoelectronics

Theory Travelling through Time and Space: The Reception of the Concept of Amoral Familism

The American political scientist Edward Banfield formulated the concept of amoral familism in 1958, in The moral basis of a backward society and defined it as follows: ‘maximize the material, short-run advantage of the nuclear family; assume that all others will do likewise’. With this concept, he intended to explain the political ineffectiveness of the inhabitants of a small town in southern Italy. From its publication, Banfield’s book has engendered an impressive amount of controversies, remarkable for their longevity, since they initiated in 1958 and are still on-going. This article provides a critical overview and theoretical reflection on these controversies. After contextualizing in the introduction these controversies in a broader theoretical and historical context, I first provide an overview of Banfield’s research and its early reception (until the mid-1970s) in the international academic community, mainly amongst anthropologists and rural sociologists. A second section addresses the Italian reception, including the revival the concept underwent following the publication of Robert D. Putnam’s classic Making democracy work in 1993, and the importance this book attributed to the concept. A third section analyzes how within Italy scholars also provided important critical assessments of his fieldwork and critiques of his concept informed by postcolonial theory. In the conclusion, I propose to interpret the longevity of the concept and the persistence of the controversies it engendered.SCOPUS: ar.jinfo:eu-repo/semantics/publishe