다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Diamond-like carbon (DLC) is a metastable form of amorphous carbon with significant sp3 bonding. DLC is a semiconductor with a high mechanical hardness, chemical inertness, and optical transparency. This review will describe the deposition methods, deposition mechanisms, characterisation methods, electronic structure, gap states, defects, doping, luminescence, field emission, mechanical properties and some applications of DLCs. The films have widespread applications as protective coatings in areas, such as magnetic storage disks, optical windows and micro-electromechanical devices (MEMs).

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Diamond-like amorphous carbon

The ionic defects at the surfaces and grain boundaries of organic–inorganic halide perovskite films are detrimental to both the efficiency and stability of perovskite solar cells. Here, we show that quaternary ammonium halides can effectively passivate ionic defects in several different types of hybrid perovskite with their negative- and positive-charged components. The efficient defect passivation reduces the charge trap density and elongates the carrier recombination lifetime, which is supported by density-function-theory calculation. The defect passivation reduces the open-circuit-voltage deficit of the p–i–n-structured device to 0.39 V, and boosts the efficiency to a certified value of 20.59 ± 0.45%. Moreover, the defect healing also significantly enhances the stability of films in ambient conditions. Our findings provide an avenue for defect passivation to further improve both the efficiency and stability of solar cells. Losses in solar cells can be caused by material defects in the bulk or at interfaces. Here, Zheng et al. use quaternary ammonium halides to passivate various perovskite absorbers and prepare solar cells with certified efficiency above 20%, suggesting that both anionic and cation defects are affected.

https://par.nsf.gov/servlets/purl/10056130

Defect passivation in hybrid perovskite solar cells using quaternary ammonium halide anions and cations

Organic photovoltaics (OPVs) evolve in an exponential manner in the two key areas of efficiency and stability. The power conversion efficiency (PCE) has in the last decade been increased by almost a factor of ten approaching 10%. A main concern has been the stability that was previously measured in minutes, but can now, in favorable circumstances, exceed many thousands of hours. This astonishing achievement is the subject of this article, which reviews the developments in stability/degradation of OPVs in the last five years. This progress has been gained by several developments, such as inverted device structures of the bulk heterojunction geometry device, which allows for more stable metal electrodes, the choice of more photostable active materials, the introduction of interfacial layers, and roll-to-roll fabrication, which promises fast and cheap production methods while creating its own challenges in terms of stability.

Stability of polymer solar cells.

We optimized Ag/ZnO back reflectors (BR) for hydrogenated nanocrystalline silicon (nc-Si:H) solar cells by independently changing the textures of the Ag and ZnO layers. We found that Ag/ZnO with textured Ag and thin ZnO provides the highest nc-Si:H solar cell efficiency. Optimized Ag texture with an rms = 40 nm effectively scatters light without seriously degrading the nc-Si:H material quality. Using this type of BR and nc-Si:H cells with ∼1-µm-thick intrinsic layer, we obtained a short-circuit current density J sc = 24.6 mA/cm2 and conversion efficiency E ff = 9.47%. By increasing the nc-Si:H layer to∼3.1 µm, we attained a J sc >30 mA/cm2. In order to increase the J sc further, we increased the texture of the ZnO layer. With highly textured Ag/ZnO BRs, the J sc was increased. However, the high textures caused poor fill factors, and hence, relatively low efficiency. By using nanocrystalline silicon-oxide (nc-SiO x :H) to replace both the n-layer and dielectric layer, the texture-induced deterioration of nc-Si:H material quality was suppressed and the cell structure was simplified by removing the ZnO, conventional n-layer, n/i buffer layer, and the seed layer. A high J sc over 27 mA/cm2 and high-cell efficiency of 8.8% were attained using a 2.5-µm-thick nc-Si:H cell with an nc-SiO x :H n-layer.

Advances in Light Trapping for Hydrogenated Nanocrystalline Silicon Solar Cells

The nature of light- and current-induced metastabilities under electrical bias in hydrogenated nanocrystalline silicon (nc-Si:H) solar cells has been found to be different from those in hydrogenated amorphous silicon (a-Si:H)-based solar cells. First, a forward-bias current injection in the dark does not cause any degradation in nc-Si:H cell performance. The phenomenon is explained by the percolation transport through crystalline paths, where the excess carrier recombination does not cause degradation. Second, a reverse bias does not reduce, but enhances the light-induced degradation in the nc-Si:H cell performance. The enhancement increases with the magnitude of the applied reverse bias. By measuring the quantum efficiency losses and color (blue, wavelength=390nm and red, wavelength=670nm) fill factors, we suggest that the reverse-bias-enhanced defect generation mostly takes place in the grain-boundary regions. Light-soaking experiments using light with different spectra show that a reverse bias under wh...

Enhancement of light-induced degradation under reverse bias in hydrogenated nanocrystalline silicon solar cells

This paper summarizes our recent studies of hydrogenated microcrystalline silicon (μc-Si:H) solar cells as a potential substitute for hydrogenated silicon germanium alloy (a-SiGe:H) bottom cells in multi-junction structures. Conventional radio frequency (RF) glow discharge is used to deposit hydrogenated amorphous silicon (a-Si:H) and μc-Si:H at low rates (∼ 1 A/s), searching for the highest efficiency. We have achieved an initial active-area efficiency of 13.0% and stable efficiency of 11.2% using an a-Si:H/μc-Si:H double-junction structure. Modified very high frequency (MVHF) glow discharge is used to deposit a-Si:H and μc-Si:H at high rates (∼ 3-10 A/s) for comparison with our a-Si:H/a-SiGe:H/a-SiGe:H triple-junction production technology. The deposition time for the μc-Si:H intrinsic (i) layer in the bottom cell should be less than 30 minutes in order to be acceptable for mass production. To date, an initial active-area efficiency of 12.3% has been achieved with the bottom cell deposited in 50 minutes. By increasing the deposition rate and reducing the bottom cell thickness, we have achieved an initial active-area efficiency of 11.4% with the bottom cell i layer deposited in 30 minutes. The cell stabilized to 10.4% after prolonged light soaking. We will address issues related to μc-Si:H material, solar cell design, solar cell analysis, and stability.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S1946427400132658

Hydrogenated Microcrystalline Silicon Single-Junction and Multi-Junction Solar Cells

We report our recent progress on high rate deposition of hydrogenated amorphous silicon (a-Si:H) and silicon germanium (a-SiGe:H) based n-i-p solar cells. The intrinsic a-Si:H and a-SiGe:H layers were deposited using modified very high frequency (MVHF) glow discharge. We found that both the initial cell performance and stability of the MVHF a-Si:H single-junction cells are independent of the deposition rate up to 15 A/s. The average initial and stable active-area cell efficiencies of 10.0% and 8.5%, respectively, were obtained for the cells on textured Ag/ZnO coated stainless steel substrates. a-SiGe:H single-junction cells were also optimized at a rate of ~10 A/s. The cell performance is similar to those made using conventional radio frequency technique at 3 A/s. By combining the optimized component cells made at 10 A/s, an a-Si:H/a-SiGe:H double-junction solar cell with an initial active-area efficiency of 11.7% was achieved.

High Rate Deposition of Amorphous Silicon Based Solar Cells using Modified Very High Frequency Glow Discharge

A roll-to-roll manufacturing technology has been developed for fabricating lightweight, high efficiency and flexible triple-junction thin film a-Si:H/a-SiGe:H/a-SiGe:H solar cells on polymer substrate for the emerging space and near-space stratospheric markets. The highest initial (before light soak), 25°C, aperture-area (721.8 cm2), AM0 efficiency attained was 9.7%. The highest initial specific power was ∼1200 W/kg with a proprietary top coating ∼0.25 mil thick. In order to develop the next generation space photovoltaic technology, effort has been made on developing nc-Si:H material. We have fabricated large area a-Si:H/nc-Si:H double-junction solar cells on 5 mil thick steel and 1 mil thick polymer substrates and demonstrated an initial AM0 active-area efficiency of around 10% on a 462 cm2 device.

Baojie Yan

Papers

Advances in Light Trapping for Hydrogenated Nanocrystalline Silicon Solar Cells

Enhancement of light-induced degradation under reverse bias in hydrogenated nanocrystalline silicon solar cells

Hydrogenated Microcrystalline Silicon Single-Junction and Multi-Junction Solar Cells

High Rate Deposition of Amorphous Silicon Based Solar Cells using Modified Very High Frequency Glow Discharge

High efficiency ultra lightweight a-Si:H/a-SiGe:H/a-SiGe:H triple-junction solar cells on polymer substrate using roll-to-roll technology