Cu2ZnSnS4 thin film solar cells grown by fast thermal evaporation and thermal treatment

Cu2ZnSnS4 thin films have been produced via rapid thermal evaporation of off-stoichiometric kesterite powder followed by annealing in an Ar atmosphere. Different heating rates were applied during the thermal treatments. The chemical composition and structural properties of the deposited layers as well as the distribution of the elements through the kesterite thin film have been investigated. The initial growth of a SnS secondary phase during evaporation led to the formation of this secondary phase next to the Mo back contact. Solar cell power conversion efficiencies were limited to values about 3 % due to this secondary phase. Furthermore, an increased open circuit voltage was demonstrated by using a Zn(O,S) buffer layerThis work was supported by DAAD project (INTERKEST, Ref: 57050358), Marie Curie-ITN (KESTCELLS, GA: 316488) and MINECO project (SUNBEAM, ENE2013-49136-C4-3-R). RC and ES acknowledge financial support from Spanish MINECO within the Ramón y Cajal program (RYC-2011-08521) and (RYC-2011-09212) respectively. SG also thanks the Government of Spain for the FPI fellowship (BES-2014-068533)

Hidden polymorphism of FAPbI3 discovered by Raman spectroscopy

Formamidinium lead iodide FAPbI3 can be used in its cubic, black form as a light absorber material in single junction solar cells. It has a band gap 1.5 eV close to the maximum of the Shockley Queisser limit, and reveals a high absorption coefficient. Its high thermal stability up to 320 C has also a downside, which is the instability of the photo active form at room temperature RT . Thus, the black amp; 945; phase transforms at RT with time into a yellow non photo active amp; 948; phase. The black phase can be recovered by annealing of the yellow state. In this work, a polymorphism of the amp; 945; phase at room temperature was found as synthesized amp; 945;i , degraded amp; 945; amp; 948; and thermally recovered amp; 945;rec . They differ in the Raman spectra and PL signal, but not in the XRD patterns. Using temperature dependent Raman spectroscopy, we identified a structural change in the amp; 945;i polymorph at ca. 110 C. Above 110 C, the FAPbI3 structure has undoubtedly cubic Pm[3 with combining macron]m symmetry high temperature phase amp; 945;HT . Below that temperature, the amp; 945;i phase was suggested to have a distorted perovskite structure with Im[3 with combining macron] symmetry. Thermally recovered FAPbI3 amp; 945;rec also demonstrated the structural transition to amp; 945;HT at the same temperature ca. 110 C during its heating. The understanding of hybrid perovskites may bring additional assets in the development of new and stable structure

Rudolf Otto’s ‘The Absolute Other’ and a radical postsecular urban contextualization

This article proposes an idea of radical urban contextualisation that follows Rudolf Otto’s discussion on an encounter with the Absolute Other. The article critically reviews current applications of postsecularism to urban theory formulated in a general framework of Jurgen Habermas’ intervention in the early 21st century. The article argues that contemporary postsecular urban theory cannot fully answer fundamental challenges that contemporary cities are facing – both political and environmental – mostly because it focuses on linguistic and cultural aspects of a city. The article proposes the ‘radicalization’ of postsecularism, engaging directly with the ‘religious experience’ defined by Rudolf Otto as an encounter with The Absolute Other – the unknown and unpredictable. The Absolute Other notion allows to ultimately contextualize every urban situation in order to formulate conditions for future-oriented (post-capitalist) urbanism

Unsettling planning theory

Recent political developments in many parts of the world seem likely to exacerbate rather than ameliorate the planetary-scale challenges of social polarization, inequality and environmental change societies face. In this unconventional multi-authored essay, we therefore seek to explore some of the ways in which planning theory might respond to the deeply unsettling times we live in. Taking the multiple, suggestive possibilities of the theme of unsettlement as a starting point, we aim to create space for reflection and debate about the state of the discipline and practice of planning theory, questioning what it means to produce knowledge capable of acting on the world today. Drawing on exchanges at a workshop attended by a group of emerging scholars in Portland, Oregon in late 2016, the essay begins with an introduction section exploring the contemporary resonances of ‘unsettling’ in, of and for planning theory. This is followed by four, individually authored responses which each connect the idea of unsettlement to key challenges and possible future directions. We end by calling for a reflective practice of theorizing that accepts unsettlement but seeks to act knowingly and compassionately on the uneven terrain that it creates

Deconstructing spatial planning: reinterpreting the articulation of a new ethos for English local planning

This article reviews recent debates about the emergence of “spatial planning” as a new ethos for English planning, suggesting that continued uncertainty around the term's use is partly caused by a failure to consider its emergence as the product of a contested political process. Drawing on an interpretive approach to policy analysis, the article goes on to show how this new organizing principle is a complex articulation of different and potentially contradictory reform impulses. The result is to destabilize the concept of spatial planning, showing how it has been constructed as an “empty signifier”, an unstable and tension-filled discursive stake in an ongoing politics of reform. Finally, it is argued that this has significant implications for the ways in which implementation success and failure should be understood and for analysis of planning reform initiatives and systems more widely