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Titanium Dioxide Hole-Blocking Layer in Ultra-Thin-Film Crystalline Silicon Solar Cells
摘要： One of the remaining obstacles to achieving the theoretical ef?ciency limit of crystalline silicon (c-Si) solar cells is high interface recombination loss for minority carriers at the Ohmic contacts. The contact recombination loss of the ultra-thin-?lm c-Si solar cells is more severe than that of the state-of-art thick cells due to the smaller volume and higher minority carrier concentration. This paper presents a design of an electron passing (Ohmic) contact for n-type Si that is hole-blocking with signi?cantly reduced hole recombination. By depositing a thin titanium dioxide (TiO2) layer, we form a metal-insulator-semiconductor (MIS) contact for a 2 μm-thick Si cell to achieve an open circuit voltage (Voc) of 645 mV, which is 10 mV higher than that of an ultra-thin cell with a traditional metal contact. This TiO2 MIS contact constitutes a step towards high-ef?ciency ultra-thin-?lm c-Si solar cells.
关键词： titanium dioxide,Silicon photovoltaic,ultra-thin-?lm,selective contact
更新于2025-09-11 14:15:04
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Numerical Optimization of 0.5‐μm‐thick Cu (In1-xGax) Se2 Solar Cell
摘要： This paper presents a numerical simulation of 2D ultra-thin Cu (In1-xGax) Se2 solar cell under drift-diffusion transport across heterojunction interfaces. The validation of the CIGS model is performed by matching the electrical characteristics of the experimental and simulation results. The surface recombination velocity of CdS/CIGS heterojunction interface and element composition Ga/(In+Ga) ratio effect on the optical properties and electrical performances of CIGS absorber are investigated. The thickness dependence and carrier concentration of the semiconductor layers on the cell performance are investigated. The nanostructured Ag, Au, or Cu back mirror is used to replace conventional Mo back contact to improve light absorption in the ultra-thin CIGS layer. Best power conversion efficiency of 21.74 % has been obtained with a thinner absorber of about 0.5‐ μm‐ thick under AM1.5 illumination condition, 300K.
关键词： Efficiency,Ultra-thin film solar cells,Heterostructure,Nanostructured back mirror,TCAD
更新于2025-09-11 14:15:04
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Active {1?1?1}-faceted ultra-thin NiO single-crystalline porous nanosheets supported highly dispersed Pt nanoparticles for synergetic enhancement of gas sensing and photocatalytic performance
摘要： Proper morphology, surface and interface structure designing are required to obtain e?cient gas sensing and photocatalytic materials. In the present work, ultra-thin NiO single-crystalline porous nanosheets with dominant {1 1 1} crystal facets (denoted as SP-NiO) and hierarchical NiO porous microspheres (denoted as HP-NiO) supported highly dispersed Pt nanoparticles with controllable sizes were designed and synthesized. Their gas sensing and photocatalytic performance were investigated. It was found that both the formaldehyde sensing and methyl orange photocatalytic degradation performance were greatly enhanced by decorating Pt nanoparticles on SP-NiO, while Pt nanoparticles decoration contributed little to the improved photocatalytic performance of HP-NiO. The results indicated that surface structure of the NiO support could also produce signi?cant impact on the activity of Pt/NiO heterojunctions. Moreover, Pt decorated SP-NiO with stable structure showed a marked long-term stability with negligible attenuation of gas sensitivity (less than 5%) for 45 days, while Pt decorated HP-NiO exhibited obvious attenuation of gas sensitivity (more than 30%) due to the structural collapse. The work not only o?ers promising materials for gas sensing and photocatalytic application, but also brings new dawn for the designing of e?cient p-type metal oxides gas sensing and photocatalytic materials through the synergistic e?ect of single-crystalline porous structures modulation, crystal facets engineering and facet-selective deposition of highly-dispersed Pt nanoparticles.
关键词： Photocatalysis,Ultra-thin,{1 1 1} crystal facets,NiO,Gas sensing
更新于2025-09-10 09:29:36
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The importance of accurate determination of optical constants for the design of nanometallic light-trapping structures
摘要： The optical constants of many metals commonly used in solar cells, e.g. as contacts, rear side planar reflectors, or more complex nanopatterned light-trapping structures, can vary depending on deposition method, thickness and other factors, and as such are not documented consistently in the literature. In the case of nanometallic light-trapping structures specifically designed to improve absorption in a solar cell, the choice of optical constants used in simulations significantly affects the predicted enhancement, as well as the structure's optimal dimensions. The trade-off between coupling into guided modes in the photovoltaic material and the number of photons absorbed parasitically in the metal leads to small differences in the optical constants giving significantly different results for the quantum efficiency and photogenerated current. This work documents several optical constant sources for silver, aluminium, gold and titanium, and the effect this has on plasmon quality factors. The effect of choosing different optical constant sources on modelling outcomes is quantified by considering the optimization of a test structure comprising a grid of metal nanodisks on the front surface of a thinned-down GaAs cell. Finally, we define a new spectrally-integrated figure of merit for comparing the expected performance of metals in light-trapping structures based on their optical constants, which we name the spectral absorption enhancement factor (SAEF).
关键词： RCWA,Light-trapping,Metallic gratings,Surface plasmons,Ultra-thin solar cells
更新于2025-09-10 09:29:36
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A WIDEBAND WIDE-ANGLE ULTRA-THIN METAMATERIAL MICROWAVE ABSORBER
摘要： A novel design of wideband, ultra-thin, wide-angle metamaterial microwave absorber has been presented. The unit cell of the proposed structure is designed by using parametric optimization in such a way that absorption frequencies come closer and give wideband response. For normal incidence, the simulated FWHM bandwidth of the proposed structure is 1.94 GHz, i.e., from 5.05 GHz to 6.99 GHz and ?10 dB absorption bandwidth is 1.3 GHz from 5.27 GHz to 6.57 GHz. The proposed structure has been analyzed for di?erent angles of polarization, and it gives high absorption (more than 50%) for oblique angles of incidence up to 60?. The designed absorber is in low pro?le with a unit cell size of λ0/6 and ultrathin with a thickness of λ0/32 at the center frequency of 5.92 GHz corresponding to 10dB absorption bandwidth. The current and electromagnetic ?eld distributions have been analyzed to understand the absorption mechanism of the absorber. An array of the proposed absorber has been fabricated and experimentally tested for various polarization angles and oblique incidences of electromagnetic wave. The proposed absorber is well suited for surveillance and other defense applications.
关键词： wideband,metamaterial,wide-angle,microwave absorber,ultra-thin
更新于2025-09-04 15:30:14