Energy production and conversion applications of one-dimensional semiconductor nanostructures

Abstract

W ith the projected world demand for energy reaching 612 quadrillion Btu (~649×10 18 J or 33 GW-yrs) in 2020 and the associated problem of carbon emission, it has become necessary to look for every enabling technology that may assist in reaching that goal in a sustainable way. Th is daunting task can broadly be classifi ed into two areas of research. Th e fi rst area includes enhancing the effi ciencies of existing 'power-consuming' technologies as well as energy generation and conversion. For example, the use of light-emitting diodes (LEDs) may push external effi ciencies up to 50%, against 13% for conventional technologies such as fl uorescent lamps. Th e use of sustainable energy generation by solar photovoltaics not only contributes to energy supply but also controls carbon emission. Th e second area includes efficient energy-storage systems, such as fuel cells and lithium batteries, for the portable electronic devices that continue to percolated throughout human society.Th e advent of nanoscience has shed light on almost every fi eld of science and technology, particularly in the development of renewable energies. Among the vast varieties of nanomaterials that have been developed, onedimensional (1D) nanomaterials with their inherent large specifi c surface areas and continuous transport path for charge carriers are useful for energy harvesting and conversion applications, which are mostly associated with surface reaction and carrier transport. When the diameter of a material is reduced below a critical value, the additional advantage of 1D materials, such as surface band bending-enhanced photoconductivity or even ballistic transport, may appear, which further enhances their carrier transport properties and hence energy conversion effi ciency. Extensive investigations have been made in this direction aiming to enhance the effi ciency of energy conversion and harvesting while lowering the cost of the aforementioned devices. In this review, selected 1D nanomaterials and their applications in energy conversion and generation technologies such as photonics, photovoltaics, photocatalysis and fuel cells will be covered. Solid-state lighting and LEDsIncreased technology effi ciency will eventually lower the demand for energy. For example, approximately 20% of world energy demand is for lighting purposes, which can be reduced through the effi cient use of LEDs instead of the fl uorescent, incandescent or high-pressure discharge lamps commonly used today. Group III nitride materials such as AlN, GaN and InN dominate in the fi eld of LEDs. However, ternary and quaternary compounds arising out of a mix of these, for example Al x Ga 1-x N and In x Ga 1-x N, can have their bandgaps, and hence emission, tuned from deep ultraviolet (UV) to the infrared by adjusting the composition fraction x [1]. Th ese materials are hard to grow due to the scarcity of lattice-matched substrates, which has led to defects in the crystal that deteriorate the device's optoelectronic properties. One-dimensional nanowires (NWs), on the other h...

Wurtzite Cu2ZnSnSe4 nanocrystals for high-performance organic–inorganic hybrid photodetectors

“…[1][2][3][4] On the other hand, colloidal NCs can be well dispersed in many solvent and deposited to films via low cost process such as spin-casting, dip-coating and printing, and easily mixed with polymers to form hybrid light-absorbing layers with enhanced performance. [5][6][7][8][9] An important parameter in their use is the band gap energy of NCs, which can be tuned by their size, shape and composition.…”

“…25,26 On the other hand, it is well known that the composition and structure of NCs significantly affect their optical and electrical properties, and the structure can be tuned by source materials, capping ligands, as well as synthetic temperature. 8,13,14,27,28 The reported Cu 2 ZnSn(S,Se) 4 NCs mostly show the stannite or kesterite structures. [19][20][21][22]25 Recently, Li and coworkers 26 reported the Cu 2 ZnSnS 4 NCs with wurtzite structure, which has been found in many binary and ternary chalcogenides, but seldom in quaternary compounds.…”

Biaxial stress controlled three-dimensional helical cracks

“…This study not only widens our understanding of cracking phenomena, but also sheds light on the control and design of regular cracks with arbitrary dimensions. 32 This cracking mode holds promise for applications in eliminating or controlling cracks during manufacturing processes. Biaxial stress controlled three-dimensional helical cracks L Wang et al…”

Plasmon management in index engineered 2.5D hybrid nanostructures for surface-enhanced Raman scattering

“…However, the effect of the SWs or the LMR in modulating the total effective E field has been ignored or addressed inadequately. The fact that Ag-or AuNP-dispersed vertically aligned 1D NW/nanorods 10 supported on a 2D wafer, to be called 2.5D hereafter, are better SERS performers [11][12][13][14][15][16][17] indicates a role for both the LMR and the SWs; however, this role has not yet been reported. Such a study is difficult but immensely useful because the hybrid (metal-semiconductor) nanostructures can be used for a wide range of applications such as SERS, [16][17][18] photonics, 4,5 renewable energy 3 and biomedicine.…”