https://www.fkit.unizg.hr/_download/repository/Smart_Windows-_Review.pdf

Properties, requirements and possibilities of smart windows for dynamic daylight and solar energy control in buildings: A state-of-the-art review

Electrochromic coatings and devices: survey of some recent advances

A significant amount of energy is consumed to maintain thermal comfort in buildings, a huge portion of which is lost through windows. Smart coating, thin films with spectrally selective properties on the surface of glass, is the innovative solution to the problem. Thermochromic smart windows change their color and optical properties in response to temperature variations. The performance, materials, coating technologies and energy modeling of thermochromic windows are reviewed in the present study. The effect of doping vanadium dioxide (VO2) coatings with different dopants such as tungsten, fluorine, gold nanoparticles and etc. is elaborated. Various deposition techniques, specifically hybrid chemical vapor deposition (AA/APCVD) and physical vapor deposition (PVD) methods are elucidated. Different dopants and techniques show different results on metal to semiconductor transition (MST) and the critical temperature. The “change in visible and infra-red transmission and reflectance” is the touchstone of performance for the different afforded chromogenic intelligent windows.

Performance, materials and coating technologies of thermochromic thin films on smart windows

3D photonic nanostructures with desirable functionalities in the visible light region and beyond have been recently given vast and increasing attentions because of the ability to control or confine electromagnetic waves in all three dimensions. Although substantial progress has been made in fabricating 3D nanostructures by means of lithography and nanotechnology, various bottlenecks still need to be overcome, and developing soft 3D stimuli-directed nanostructures with tailored properties remains a challenging but exciting work. In this context, soft nanotechnology—i.e., exploiting self-organized soft materials in nanotechnology—is emerging as a vibrant and burgeoning field of research in the bottom-up nanofabrication of intelligent stimuli-driven 3D photonic materials and devices. Liquid-crystalline materials undoubtedly represent such a marvelous dynamic system that combines the liquid-like fluidity and crystal-like ordering from molecular to macroscopic material levels. Importantly, being “soft” makes the materials responsive to various stimuli such as temperature, light, mechanical force, and electric and magnetic fields as well as chemical and electrochemical reactions, resulting in a fascinating tunability of dynamic photonic bandgaps in the 3D nanostructure that provides numerous opportunities in all-optical integrated circuits and next-generation communication systems. Here, the development of 3D photonic nanostructures is reviewed, culminating with perspectives for the future scope and challenges of these emerging soft 3D photonic nanostructures towards device applications.

Stimuli-Directing Self-Organized 3D Liquid-Crystalline Nanostructures: From Materials Design to Photonic Applications

The hydride configurations in the hydrogenated amorphous silicon (a-Si:H) network have been studied by means of infrared absorption spectroscopy. The results on the film mass density of a-Si:H deposited by means of an expanding thermal plasma reveal the presence of two distinct regions in terms of hydrogen content and microstructure: below approximately 14 at. % H a-Si:H contains predominantly divacancies decorated by hydrogen, above 14 at. % H a-Si:H contains microscopic voids. These two distinct regions provide additional information on the origin of the low and high hydride stretching modes at 1980–2010 and 2070–2100 cm−1, respectively.

/pdf/vacancies-and-voids-in-hydrogenated-amorphous-silicon-3p09t5ekn2.pdf

Vacancies and voids in hydrogenated amorphous silicon

Efficient crystalline silicon heterojunction solar cells are fabricated on p-type wafers using amorphous silicon emitter and back contact layers. The independently confirmed AM1.5 conversion efficiencies are 19.3% on a float-zone wafer and 18.8% on a Czochralski wafer; conversion efficiencies show no significant light-induced degradation. The best open-circuit voltage is above 700 mV. Surface cleaning and passivation play important roles in heterojunction solar cell performance.

/pdf/efficient-heterojunction-solar-cells-on-p-type-crystal-1zcaglkh31.pdf

Efficient heterojunction solar cells on p-type crystal silicon wafers

The structure of a-Si:H, deposited at rates in excess of 100 A/s by the hot wire chemical vapor deposition technique, has been examined by x-ray diffraction (XRD), Raman spectroscopy, H evolution, and small-angle x-ray scattering (SAXS). The films examined in this study were chosen to have roughly the same bonded H content CH as probed by infrared spectroscopy. As the film deposition rate Rd is increased from 5 to >140 A/s, we find that the short range order (from Raman), the medium range order (from XRD), and the peak position of the H evolution peak are invariant with respect to deposition rate, and exhibit structure consistent with a state-of-the-art, compact a-Si:H material deposited at low deposition rates. The only exception to this behavior is the SAXS signal, which increases by a factor of ∼100 over that for our best, low H content films deposited at ∼5 A/s. We discuss the invariance of the short and medium range order in terms of growth models available in the literature, and relate changes in th...

/pdf/structural-properties-of-hot-wire-a-si-h-films-deposited-at-2kjc21m7jv.pdf

Structural properties of hot wire a-Si:H films deposited at rates in excess of 100 Å/s

We prototype an alternative n-type monocrystalline silicon (c-Si) solar cell structure that utilizes an n/i-type hydrogenated amorphous silicon (a-Si:H) front hetero-contact and a back p-n junction formed by alloying aluminum (Al) with the n-type Si wafer. Such a structure combines a conventional high-throughput Al-Si alloying process with excellent front surface passivation provided by a-Si:H. A key process consideration is to preserve the clean c-Si front surface through the high-temperature alloying, so there will be effective a-Si:H passivation. From cell simulations, we estimate a front SRV of 10–50 cm/sec has been achieved in our process. The best prototype 1×1 cm2 cell with planar front surface and single anti-reflection (AR) coating layer has demonstrated a confirmed conversion efficiency of 13.5%, V oc of 604.7 mV, and fill factor (FF) of 79.9%. Processes for further efficiency improvements are described.

/pdf/silicon-solar-cells-with-front-hetero-contact-and-aluminum-d1pfjeodac.pdf

Yueqin Xu

Papers

Efficient heterojunction solar cells on p-type crystal silicon wafers

Structural properties of hot wire a-Si:H films deposited at rates in excess of 100 Å/s

Silicon solar cells with front hetero-contact and aluminum alloy back junction

First a-SiC : H photovoltaic-powered monolithic tandem electrochromic smart window device

High-deposition rate a-Si:H n–i–p solar cells grown by HWCVD