Informal housing and industrial developments in the so-called urban villages have been key features of the recent Chinese urbanization. In this article we will examine the development of urban villages in one of the most dynamic Chinese cities - Shenzhen. The article first reviews the urbanization and migration process in the region and the emergence of urban villages. It then examines informal housing, commercial and industrial developments in these villages. We analyse the politics of village urbanization and highlight the important relationship between migration and informal village development. We emphasize the contribution made by urban villages in providing affordable housing and jobs for the low-income population during the rapid urbanization and urge cautious consideration with regard to hasty and large-scale redevelopment of these villages. We conclude that the development of urban villages is a very important part of the urbanization process. Copyright (c) 2009 The Authors. Journal Compilation (c) 2009 Joint Editors and Blackwell Publishing Ltd.

Lead‐based halide perovskites have received great attention in light‐emitting applications due to their excellent properties, including high photoluminescence quantum yield (PLQY), tunable emission wavelength, and facile solution preparation. In spite of excellent characteristics, the presence of toxic element lead directly obstructs their further commercial development. Hence, exploiting lead‐free halide perovskite materials with superior properties is urgent and necessary. In this review, the deep‐seated reasons that benefit light emission for halide perovskites, which help to develop lead‐free halide perovskites with excellent performance, are first emphasized. Recent advances in lead‐free halide perovskite materials (single crystals, thin films, and nanocrystals with different dimensionalities) from synthesis, crystal structures, optical and optoelectronic properties to applications are then systematically summarized. In particular, phosphor‐converted LEDs and electroluminescent LEDs using lead‐free halide perovskites are fully examined. Ultimately, based on current development of lead‐free halide perovskites, the future directions of lead‐free halide perovskites in terms of materials and light‐emitting devices are discussed.

Zirconium acetylacetonate used as a co-precursor in the synthesis of CsPbI 3 quantum dots (QDs) increased their photoluminescence quantum efficiency to values over 90%. The top-emitting device structure on a Si substrate with high thermal conductivity (to better dissipate Joule heat generated at high current density) was designed to improve the light extraction efficiency making use of a strong microcavity resonance between the bottom and top electrodes. As a result of these improvements, light-emitting diodes (LEDs) utilizing Zr-modified CsPbI 3 QDs with an electroluminescence at 686 nm showed external quantum efficiency (EQE) of 13.7% at a current density of 108 mA cm −2 , which was combined with low efficiency roll-off (maintaining an EQE of 12.5% at a high current density of 500 mA cm −2 ) and a high luminance of 14 725 cd m −2 , and the stability of the devices being repeatedly lit (cycled on and off at high drive current density) has been greatly enhanced.

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We report on the fabrication and electroluminescence of an n-ZnO nanorod/p-Si heterojunction. ZnO nanorods were grown on p-type Si substrates employing an easy low-temperature aqueous solution method. As-grown ZnO nanorods showed good crystallinity and a preferable c axial orientation. Electroluminescent devices were constructed using high-molecular-weight polymers as the fill-in, and the I–V characteristics were diode-like. A typical electroluminescent spectrum of such an n-ZnO/p-Si heterojunction under forward bias was composed of a narrow ultraviolet peak centred at 387 nm and a broad green band at 535 nm, consistent with the photoluminescent spectrum. The intensity of the ultraviolet light grew more quickly than that of the green light with the increasing of bias.

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We present a theoretical study of spin transport in a series of organometallic iron-cyclopentadienyl, Fe(n)Cp(n+1), multidecker clusters sandwiched between either gold or platinum electrodes. Ab initio modeling is performed by combining the non-equilibrium Green's function formalism with spin density functional theory. Due to the intrinsic bonding nature, the low-bias conductance of the Fe(n)Cp(n+1) clusters contacted to gold electrodes is relatively small even for strong cluster-electrode coupling. However, a nearly 100% spin polarization of the transmitted electrons can be achieved for the Fe(n)Cp(n+1) (n>2) clusters. In contrast, the Fe(n)Cp(n+1) (n>2) clusters attached to platinum electrodes through Pt adatoms not only can act as nearly perfect spin filters but also show a much larger transmission around the Fermi level, demonstrating their promising applications in future molecular spintronics.