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Using a new framework combining vulnerability and exclusion as two central dimensions of poverty, this article revisits some of the long-standing beliefs about poverty in small-scale fisheries. We argue that the issue of poverty in fish-dependent communities cannot be reduced to a simple correlation between income poverty and fishery dependence. A more thorough analysis is required that must account for the diversity of fishing-related livelihoods and the complexity of causes of poverty, both inside and outside the sector. The article highlights how poverty in fishing communities often relates to a wide range of socio-institutional factors other than income, including landownership, debt, access to health, education and financial capital, and marginalisation from political decision making. The empirical examples used in this article refer to inland capture fisheries from the Volta and Mekong basins but, arguably, the analysis applies to other fisheries (inland and coastal) in developing countries.

Agricultural and food systems in the Mekong Region are undergoing transformations because of increasing engagement in international trade, alongside economic growth, dietary change and urbanisation. Food systems approaches are often used to understand these kinds of transformation processes, with particular strengths in linking social, economic and environmental dimensions of food at multiple scales. We argue that while the food systems approach strives to provide a comprehensive understanding of food production, consumption and environmental drivers, it is less well equipped to shed light on the role of actors, knowledge and power in transformation processes and on the divergent impacts and outcomes of these processes for different actors. We suggest that an approach that uses food systems as heuristics but complements it with attention to actors, knowledge and power improves our understanding of transformations such as those underway in the Mekong Region. The key transformations in the region include the emergence of regional food markets and vertically integrated supply chains that control increasing share of the market, increase in contract farming particularly in the peripheries of the region, replacement of crops cultivated for human consumption with corn grown for animal feed. These transformations are increasingly marginalising small-scale farmers, while at the same time, many other farmers increasingly pursue non-agricultural livelihoods. Food consumption is also changing, with integrated supply chains controlling substantial part of the mass market. Our analysis highlights that theoretical innovations grounded in political economy, agrarian change, development studies and rural livelihoods can help to increase theoretical depth of inquiries to accommodate the increasingly global dimensions of food. As a result, we map out a future research agenda to unpack the dynamic food system interactions and to unveil the social, economic and environmental impacts of these rapid transformations. We identify policy and managerial implications coupled with sustainable pathways for change

Abstract
Of growing research and policy interest are the experiences of people living under conditions of climate change–induced environmental stress, which either are unable to migrate (sometimes described as a 'trapped population') or are seemingly unwilling to do so (sometimes described as the 'voluntarily immobile'). This paper problematises and expands upon these binary categories: examining the complex dimensionality of non-migration as a form of place relations, explored through qualitative study of rural and coastal Bangladeshi communities. Through 60 semi-structured interviews of individuals from four communities in the Kalapara region, the analysis proffers four qualitatively derived and inter-related dimensions of voluntary and involuntary non-migration framed as a form of place relations. These four dimensions concern the following: (1) livelihood opportunities, (2) place obduracy, (3) risk perceptions, and (4) social-structural constraints, with the interplay between these elements explaining diverse non-migratory experiences. In our analysis, 'place obduracy' is introduced as a concept to describe the differential speed of environmental change and socio-cultural adaptation responses to explain non-migratory experiences. Our discussion provides insight into how to best support non-migrant people's adaptive capacity in the face of growing climate emergency.

Organic solar cells (OSCs) have been dominated by donor: acceptor blends based on fullerene acceptors for over two decades. This situation has changed recently, with non-fullerene (NF) OSCs developing very quickly. The power conversion efficiencies of NF OSCs have now reached a value of over 13%, which is higher than the best fullerene-based OSCs. NF acceptors show great tunability in absorption spectra and electron energy levels, providing a wide range of new opportunities. The coexistence of low voltage losses and high current generation indicates that new regimes of device physics and photophysics are reached in these systems. This Review highlights these opportunities made possible by NF acceptors, and also discuss the challenges facing the development of NF OSCs for practical applications. ; Funding Agencies|National Natural Science Foundation of China [91633301, 91333204, 51673201, 21325419, 51711530159]; Chinese Academy of Sciences [XDB12030200]; Swedish Research Council VR [2017-00744, 2016-06146]; Swedish Energy Agency Energimyndigheten [2016-010174]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU #2009-00971]; Engineering and Physical Sciences Research Council in the UK; Knut and Alice Wallenberg foundation (KAW) through a Wallenberg Scholar grant

The development of perovskite emitters, their use in light-emitting devices, and the challenges in enhancing the efficiency and stability, as well as reducing the potential toxicity of this technology are discussed in this Review. Metal halide perovskites have shown promising optoelectronic properties suitable for light-emitting applications. The development of perovskite light-emitting diodes (PeLEDs) has progressed rapidly over the past several years, reaching high external quantum efficiencies of over 20%. In this Review, we focus on the key requirements for high-performance PeLEDs, highlight recent advances on materials and devices, and emphasize the importance of reliable characterization of PeLEDs. We discuss possible approaches to improve the performance of blue and red PeLEDs, increase the long-term operational stability and reduce toxicity hazards. We also provide an overview of the application space made possible by recent developments in high-efficiency PeLEDs. ; Funding Agencies|European Research Council Starting GrantEuropean Research Council (ERC) [717026]; Swedish Energy Agency EnergimyndighetenSwedish Energy Agency [48758-1]; Swedish Foundation for International Cooperation in Research and Higher Education [CH2018-7736]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; UK Engineering and Physical Sciences Research CouncilEngineering & Physical Sciences Research Council (EPSRC); Joint Research Program between China and the European Union [2016YFE0112000]; National Key Research and Development Program of China [2016YFB0401600]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [21975220, 91833303, 91733302, 51911530155]

Lead-halide perovskites have triggered the latest breakthrough in photovoltaic technology. Despite the great promise shown by these materials, their instability towards water even in the presence of low amounts of moisture makes them, a priori, unsuitable for their direct use as light harvesters in aqueous solution for the production of hydrogen through water splitting. Here, we present a simple method that enables their use in photoelectrocatalytic hydrogen evolution while immersed in an aqueous solution. Field's metal, a fusible InBiSn alloy, is used to efficiently protect the perovskite from water while simultaneously allowing the photogenerated electrons to reach a Pt hydrogen evolution catalyst. A record photocurrent density of -9.8 mA cm(-2) at 0 V versus RHE with an onset potential as positive as 0.95±0.03 V versus RHE is obtained. The photoelectrodes show remarkable stability retaining more than 80% of their initial photocurrent for ∼1 h under continuous illumination. ; The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7-PEOPLE-2013-IEF under REA Grant Agreement No. (623061; M.C-Q.). This work was also supported by the Christian Doppler Research Association (Austrian Federal Ministry of Science, Research and Economy and the National Foundation for Research, Technology and Development) and the OMV Group (J.W., M.F.K. and E.R.); L.M.P.-O. would like to thank the Engineering and Physical Sciences Research Council of the UK (EPSRC), the Cambridge Home European Scholarship Scheme (CHESS) and King Abdulaziz City for Science and Technology (KACST).

In band-like semiconductors, charge carriers form a thermal energy distribution rapidly after optical excitation. In hybrid perovskites, the cooling of such thermal carrier distributions occurs on timescales of about 300 fs via carrier-phonon scattering. However, the initial build-up of the thermal distribution proved difficult to resolve with pump–probe techniques due to the requirement of high resolution, both in time and pump energy. Here, we use two-dimensional electronic spectroscopy with sub-10 fs resolution to directly observe the carrier interactions that lead to a thermal carrier distribution. We find that thermalization occurs dominantly via carrier-carrier scattering under the investigated fluences and report the dependence of carrier scattering rates on excess energy and carrier density. We extract characteristic carrier thermalization times from below 10 to 85 fs. These values allow for mobilities of 500 cm$^2$ V$^{−1}$s$^{−1}$ at carrier densities lower than 2 × 10$^{19}$ cm$^{−3}$ and limit the time for carrier extraction in hot carrier solar cells. ; This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no 654148 Laserlab-Europe (CUSBO 002151). We acknowledge further financial support from the Engineering and Physical Sciences Research Council of the UK (EPSRC). G.C. acknowledges support by the European Union Horizon 2020 Programme under Grant Agreement No. 696656 Graphene Flagship and by the European Research Council Advanced Grant STRATUS (ERC-2011-AdG No. 291198). J.M.R. and F.D. thank the Winton Programme for the Physics of Sustainability (University of Cambridge). J.M.R. thanks the Cambridge Home European Scheme for financial support. F.D. acknowledges funding from a Herchel Smith Research Fellowship and a Winton Advanced Research Fellowship. We thank Cristian Manzoni for fruitful discussions.

Quantum-confined CsPbBr3 nanoplatelets (NPLs) are extremely promising for use in low-cost blue light-emitting diodes, but their tendency to coalesce in both solution and film form, particularly under operating device conditions with injected charge-carriers, is hindering their adoption. We show that employing a short hexyl-phosphonate ligand (C6H15O3P) in a heat-up colloidal approach for pure, blue-emitting quantum-confined CsPbBr3 NPLs significantly suppresses these coalescence phenomena compared to particles capped with the typical oleyammonium ligands. The phosphonate-passivated NPL thin films exhibit photoluminescence quantum yields of ∼40% at 450 nm with exceptional ambient and thermal stability. The color purity is preserved even under continuous photoexcitation of carriers equivalent to LED current densities of ∼3.5 A/cm2. 13C, 133Cs, and 31P solid-state MAS NMR reveal the presence of phosphonate on the surface. Density functional theory calculations suggest that the enhanced stability is due to the stronger binding affinity of the phosphonate ligand compared to the ammonium ligand. ; J. S. and S.D.S. acknowledge the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (HYPERION, grant agreement number 756962). S.D.S acknowledges funding from the Royal Society and Tata Group (UF150033). R.H.F. and Y.L. acknowledge sup-port from the Simons Foundation (grant 601946). M.A. and D.K. acknowledges funding from the European Union's Hori-zon 2020 research and innovation programme under the Ma-rie Skłodowska-Curie (grant agreement number 841386 and 841136, respectively). K.J. acknowledges funding from the Royal Society (RGFR1180002). K.F. acknowledges a George and Lilian Schiff Studentship, Winton Studentship, the Engineer-ing and Physical Sciences Research Council (EPSRC) student-ship, Cambridge Trust Scholarship, and Robert Gardiner Scholarship. C. P. G. acknowledges the European Research Council (ERC) under the European Union's Horizon 2020 re-search and innovation program (835073) and the Royal Society for a Research Professorship (RP\R1\180147). The authors acknowledge the EPSRC for funding (EP/R023980/1).

Semiconductor quantum dots (QDs) are among the most promising next-generation optoelectronic materials. QDs are generally obtained through either epitaxial or colloidal growth and carry the promise for solution-processed high-performance optoelectronic devices such as light-emitting diodes (LEDs), solar cells, etc. Herein, a straightforward approach to synthesize perovskite QDs and demonstrate their applications in efficient LEDs is reported. The perovskite QDs with controllable crystal sizes and properties are in situ synthesized through one-step spin-coating from perovskite precursor solutions followed by thermal annealing. These perovskite QDs feature size-dependent quantum confinement effect (with readily tunable emissions) and radiative monomolecular recombination. Despite the substantial structural inhomogeneity, the in situ generated perovskite QDs films emit narrow-bandwidth emission and high color stability due to efficient energy transfer between nanostructures that sweeps away the unfavorable disorder effects. Based on these materials, efficient LEDs with external quantum efficiencies up to 11.0% are realized. This makes the technologically appealing in situ approach promising for further development of state-of-the-art LED systems and other optoelectronic devices. ; Funding Agencies|ERC Starting Grant [717026]; Carl Tryggers Stiftelse; European Commission Marie SklodowskaCurie Actions [691210]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; China Scholarship Council

Metal halide perovskites are generating enormous excitement for use in solar cells and light-emission applications, but devices still show substantial non-radiative losses. Here, we show that by combining light and atmospheric treatments, we can increase the internal luminescence quantum efficiencies of polycrystalline perovskite films from 1% to 89%, with carrier lifetimes of 32 μs and diffusion lengths of 77 μm, comparable with perovskite single crystals. Remarkably, the surface recombination velocity of holes in the treated films is 0.4 cm/s, approaching the values for fully passivated crystalline silicon, which has the lowest values for any semiconductor to date. The enhancements translate to solar cell power-conversion efficiencies of 19.2%, with a near-instant rise to stabilized power output, consistent with suppression of ion migration. We propose a mechanism in which light creates superoxide species from oxygen that remove shallow surface states. The work reveals an industrially scalable post-treatment capable of producing state-of-the-art semiconducting films. ; S.D.S. has received funding from the European Union's Seventh Framework Program (Marie Curie Actions) under REA grant number PIOF-GA-2013-622630. This work made use of the Shared Experimental Facilities supported in part by the MRSEC Program of the National Science Foundation (NSF) under award number MDR – 1419807. R.B. acknowledges support from the MIT Undergraduate Research Opportunities Program (UROP). A.O. acknowledges support from the NSF under grant no. 1605406 (EP/L000202). D.G. acknowledges the China Scholarship Council for funding, file no. 201504910812. The authors acknowledge funding from the Engineering and Physical Sciences Research Council (EPSRC) under EP/P02484X/1 and the Programme Grant EP/M005143/1. M.S.I. and C.E. acknowledge support from the EPSRC Program grant on Energy Materials (EP/KO16288) and the Archer HPC/MCC Consortium (EP/L000202). E.M.H. gratefully acknowledges the Netherlands Organization for Scientific Research (NWO) Echo number 712.014.007 for funding. The work was also partially supported by Eni S.p.A. via the Eni-MIT Solar Frontiers Center. The authors thank Mengfei Wu and Marc Baldo for access to an integrating sphere, Jay Patel and Michael Johnston for EQE verifications, and Eli Yablonovitch and Luis Pazos-Outón for helpful discussion.

Osmotic shock in a vesicle or cell is the stress build-up and subsequent rupture of the phospholipid membrane that occurs when a relatively high concentration of salt is unable to cross the membrane and instead an inflow of water alleviates the salt concentration gradient. This is a well-known failure mechanism for cells and vesicles (for example, hypotonic shock) and metal alloys (for example, hydrogen embrittlement)1, 2, 3. We propose the concept of collective osmotic shock, whereby a coordinated explosive fracture resulting from multiplexing the singular effects of osmotic shock at discrete sites within an ordered material results in regular bicontinuous structures. The concept is demonstrated here using self-assembled block copolymer micelles, yet it is applicable to organized heterogeneous materials where a minority component can be selectively degraded and solvated whilst ensconced in a matrix capable of plastic deformation. We discuss the application of these self-supported, perforated multilayer materials in photonics, nanofiltration and optoelectronics. ; We would like to acknowledge S. Vignolini, C. Wang (beamline 11.0.1.2, LBNL), S. Alvarez, C. Lopez and Q. Song, and the insightful comments of U. Steiner and E. J. Kramer. This work was funded by the Qatar Foundation (QNRF), the Engineering and Physical Sciences Research Council (EPSRC), the Consejo Nacional de Ciencia y Tecnología (CONACyT), the Spanish Ministerio de Ciencia e Innovación (MICINN, Consolider HOPE) and the Government of Andalucía. ; Peer Reviewed

State-of-the-art organic solar cells (OSCs) typically suffer from large voltage loss (V-loss) compared to their inorganic and perovskite counterparts. There are some successful attempts to reduce the V-loss by decreasing the energy offsets between the donor and acceptor materials, and the OSC community has demonstrated efficient systems with either small highest occupied molecular orbital (HOMO) offset or negligible lowest unoccupied molecular orbital (LUMO) offset between donors and acceptors. However, efficient OSCs based on a donor/acceptor system with both small HOMO and LUMO offsets have not been demonstrated simultaneously. In this work, an efficient nonfullerene OSC is reported based on a donor polymer named PffBT2T-TT and a small-molecular acceptor (O-IDTBR), which have identical bandgaps and close energy levels. The Fourier-transform photocurrent spectroscopy external quantum efficiency (FTPS-EQE) spectrum of the blend overlaps with those of neat PffBT2T-TT and O-IDTBR, indicating the small driving forces for both hole and electron transfer. Meanwhile, the OSCs exhibit a high electroluminescence quantum efficiency (EQE(EL)) of approximate to 1 x 10(-4), which leads to a significantly minimized nonradiative V-loss of 0.24 V. Despite the small driving forces and a low V-loss, a maximum EQE of 67% and a high power conversion efficiency of 10.4% can still be achieved. ; Funding Agencies|National Basic Research Program of China (973 Program) [2013CB834701, 2014CB643501]; Shenzhen Technology and Innovation Commission [JCYJ20170413173814007, JCYJ20170818113905024]; Hong Kong Research Grants Council [T23-407/13 N, N_HKUST623/13, 16305915, 16322416, 606012, 16306117, 16303917]; HK JEBN Limited, HKUST presidents office [FP201]; National Science Foundation of China [21374090]; Swedish Energy Agency Energimyndigheten [2016-010174]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]; Hong Kong Innovation and Technology Commission [ITC-CNERC14SC01, ITS/083/15]