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Aluminum-Doped Zinc Oxide as Front Electrode for Rear Emitter Silicon Heterojunction Solar Cells with High Efficiency
摘要： Transparent conductive oxide (TCO) layers of aluminum-doped zinc oxide (ZnO:Al) were investigated as a potential replacement of indium tin oxide (ITO) for the front contact in silicon heterojunction (SHJ) solar cells in the rear emitter configuration. It was found that ZnO:Al can be tuned to yield cell performance almost at the same level as ITO with a power conversion efficiency of 22.6% and 22.8%, respectively. The main reason for the slight underperformance of ZnO:Al compared to ITO was found to be a higher contact resistivity between this material and the silver grid on the front side. An entirely indium-free SHJ solar cell, replacing the ITO on the rear side by ZnO:Al as well, reached a power conversion efficiency of 22.5%.
关键词： photovoltaics,silicon heterojunction,rear emitter,transparent conductive oxide
更新于2025-11-14 15:25:21
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Effect of front TCO on the performance of rear-junction silicon heterojunction solar cells: Insights from simulations and experiments
摘要： In this study we make a detailed comparison between indium tin oxide (ITO), aluminum-doped zinc oxide (ZnO:Al) and hydrogenated indium oxide (IO:H) when applied on the illuminated side of rear-junction silicon heterojunction (SHJ) solar cells. ITO being the state of the art material for this application, ZnO:Al being an attractive substitute due to its cost effectiveness and IO:H being a transparent conductive oxide (TCO) with high-mobility and excellent optical properties. Through numerical simulations, the optically optimal thicknesses for a double layer anti-reflective coating system, consisting of the respective TCO and amorphous silicon oxide (a-SiO2) capping layers are defined. Through two-dimensional electrical simulations, we present a comparison between front-junction and rear-junction devices to show the behavior of series resistance (Rs) in dependence of the TCO sheet resistance (Rsh) and the device effective lifetime (τeff). The study indicates that there is a τeff dependent critical TCO Rsh value, above which, the rear-junction device will become advantageous over the front-junction design in terms of Rs. Solar cells with the respective layers are analyzed. We show that a thinner TCO optimized layer will result in a benefit in cell performance when implementing a double layer anti-reflective coating. We conclude that for a highest efficiency solar cell performance, a high mobility TCO, like IO:H, is required as the device simulations show. However, the rear-junction solar cell design permits the implementation of a lower conductive TCO in the example of the cost-effective ZnO:Al with comparable performance to the ITO, opening the possibility for substitution in mass production.
关键词： Transparent conductive oxide,Sheet resistance,Series resistance,Rear-junction,Silicon heterojunction,Anti-reflective coating
更新于2025-10-22 19:40:53
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Effect of microwave irradiation on the electrical and optical properties of SnO2 thin films
摘要： We report the electrical and optical characteristics of SnO2 thin films irradiated by microwaves (MWs) and grown using atomic layer deposition in a commercial MW oven operating at a frequency of 2.45 GHz. The properties of the MW-irradiated SnO2 thin films were compared with those of the as-deposited SnO2 thin films. After MW irradiation, the conductivity and transparency of the thin films were enhanced. In addition, the samples irradiated for 5 min showed optimal carrier concentration, Hall-mobility, resistivity, and transmittance values of 1.5 × 1020 cm-3, 4.6 cm2/V·s, 8 × 10-3 Ω·cm, and 95.77%, respectively. The improved properties of the MW-irradiated samples were attributed mainly to the formation of an oxygen vacancy in the SnO2 lattice during MW irradiation. Our results can be applied for the fabrication of pure SnO2-based transparent conductive oxides; these oxides are generally doped with other elements.
关键词： SnO2,Transparent Conductive Oxide,Microwave Irradiation,Electrical and Optical Properties
更新于2025-09-23 15:23:52
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Hybrid photonic-plasmonic electro-optic modulator for optical ring network-on-chip
摘要： One of the most essential components in an optical network-on-chip (ONoC) is the electro-optic modulator. Mach-Zehnder and micro-ring resonator electro-optic modulators are widely used in ONoC, and conventional silicon-based modulators have large footprints and low modulation rates and lack thermal stability. In this paper, a new electro-optic modulator based on surface plasmon polariton (SPP) is proposed, and indium tin oxide (ITO) is utilized as a conducting transparent oxide (TCO) material in the electro-optic modulator. The modulated optical signal is suitable for ONoC with architectures such as optical ring network-on-chip (ORNoC). When the wavelength is 1550 nm, the average coupling efficiency is over 70%, the extinction ratio of the electro-optic modulator is -14.1 dB, and the insertion loss is 2.1 dB. In addition, the size of the modulator is less than 8.50 μm×1.6 μm, and the modulation operating bandwidth is up to 0.7171 Tbit/S. When the wave division multiplex (WDM) mode is used, the operating bandwidth is up to 2.1 Tbit/S, and the energy consumption per bit (E) is 5.7211 fJ/bit. All of the above results were obtained from 3D-FDTD Simulation Software and MATLAB.
关键词： electro-optic modulator,ORNoC,optical network-on-chip,transparent conductive oxide,surface plasmon polaritons
更新于2025-09-19 17:13:59
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Sputtered indium tin oxide as a recombination layer formed on the tunnel oxide/poly-Si passivating contact enabling the potential of efficient monolithic perovskite/Si tandem solar cells
摘要： We focus on utilizing sputtered indium tin oxide (ITO) as a recombination layer, having low junction damage to an n-type silicon solar cell with a front-side tunnel oxide passivating electron contact, thereby enabling the development of a high efficiency monolithic perovskite/Si tandem device. High transparency and low resistivity ITO films are deposited via low power DC magnetron sputtering at room temperature onto a front-side thin SiOx/n+ poly-Si contact in a complete Cz n-Si cell with a back-side Al2O3/SiNx passivating boron-diffused p+ emitter on a random pyramid textured surface. We report the cell characteristics before and after ITO sputtering, and we find a cure at 250 °C in air is highly effective at mitigating any sputtering induced damage. Our ITO coated sample resulted in an implied open-circuit voltage (iVoc) of 684.7 ± 11.3 mV with the total saturation current density of 49.2 ± 14.8 fA/cm2, an implied fill factor (iFF) of 81.9 ± 0.8%, and a contact resistivity in the range of 60 mΩ-cm2 to 90 mΩ-cm2. After formation of a local Ag contact to the rear emitter and sputtered ITO film as the front-side contact without grid fingers, the pseudo-efficiency of 20.2 ± 0.5% was obtained with the Voc of 670.4 ± 7 mV and pseudo FF of 77.3 ± 1.3% under simulated one sun with the calculated short-circuit current density of 30.9 mA/cm2 from the measured external quantum efficiency. Our modelling result shows that efficiency exceeding 25% under one sun is practically achievable in perovskite/Si tandem configuration using the ITO recombination layer connecting a perovskite top cell and a poly-Si bottom cell.
关键词： Tandem solar cell,Transparent conductive oxide,Polycrystalline silicon,Passivating contacts,Perovskite,TOPCon
更新于2025-09-19 17:13:59
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Review of Rear Emitter Silicon Heterojunction Solar Cells
摘要： This inclusive study provides detailed information regarding the evolution of rear emitter silicon heterojunction solar cells. Silicon heterojunction (SHJ) solar cells of a p-type on the rear side have garnered increasing attention for various reasons. First, owing to a limitation of the p-type hydrogenated amorphous silicon layer, further optimization relative to an n-type cannot be achieved, and an accumulation of electrons at the front side allows utilizing an n-type wafer to affirm a lateral current transport. Second, better thin n-type nanocrystalline silicon (oxide) contact layers compared to p-type wafers are grown, and allow greater freedom in the structural design. The optical properties of the front side’s transparent conductive oxide (TCO) layer can be emphasized owing to a lateral transport on the cells, and majority of the carriers are affirmed through a Si substrate. In the instance of a rear emitter, the TCO layer is in relief to an adjustment inhibiting the contact resistance between TCO/a-Si:H(p). The fabrication was done in such a manner of SHJ rear emitter solar cells that they achieve greater optimization and overall efficiency of 23.46%.
关键词： Heterojunction solar cell,Lateral transport,Rear emitter,Transparent conductive oxide
更新于2025-09-19 17:13:59
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Bifacial IFO/(n+pp+)Cz-Si/ITO solar cells with full-area Al-alloyed BSF and Ag-free multi-wire metallization suitable for low-concentration systems
摘要： Bifacial solar cells have received considerable attention due to the potential to achieve higher energy yield compared to monofacial cells. However, in bifacial cells, p+-Si layers are usually produced by boron diffusion, which makes such cells more expensive compared to monofacial cells with a full-area screen-printed Al-alloyed Al-p+ back-surface-field (BSF). Recently, we have demonstrated proof-of-concept that bifacial cells, which, in addition, are also suitable for application in low-concentration systems (3–6 suns), can be produced from commercially available, standard monofacial SiNx/(n+pp+)Cz-Si/Al structures with full-area Al-p+-BSF. For this purpose, the residual Al paste was removed and a number of solar cells were prepared differing in the sheet resistance of the Al-p+-BSF (Rp+), which was varied from 14 Ω/sq to 123 Ω/sq by thinning the Al-p+ layer using one-sided etch-back process. Thinning of the Al-p+-BSF significantly improved the efficiency under 1-sun front/rear-side illumination: from 16.0%/7.5% (at Rp+ = 14 Ω/sq) to 17.5%/11.2% (at Rp+ = 81 Ω/sq). The equivalent efficiency at 1-sun front illumination and 20/50% albedo of 1-sun illumination increased from 17.7%/20.1% (at Rp+ = 14 Ω/sq) to 19.9%/23.5% (at Rp+ = 81 Ω/sq). In this paper, we present the results of systematic study of the developed bifacial cells. Thinning-induced changes in the properties of the cells are analyzed in detail. The critical aspects which might explain the performance of the developed cells are addressed. In addition, bifacial cells are compared with standard monofacial cells fabricated using the precursor of the same batch.
关键词： Ultrasonic spray pyrolysis,Transparent conductive oxide,Ag-cost reduction,Bifacial concentrator silicon solar cell,Multi-wire metallization,Al-alloyed BSF
更新于2025-09-19 17:13:59
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Influence of Silicon Layers on the Growth of ITO and AZO in Silicon Heterojunction Solar Cells
摘要： In this article, we report on the properties of indium tin oxide (ITO) deposited on thin-film silicon layers designed for the application as carrier selective contacts for silicon heterojunction (SHJ) solar cells. We find that ITO deposited on hydrogenated nanocrystalline silicon (nc-Si:H) layers presents a significant drop on electron mobility μe in comparison to layers deposited on hydrogenated amorphous silicon films (a-Si:H). The nc-Si:H layers are not only found to exhibit a larger crystallinity than a-Si:H, but are also characterized by a considerably increased surface rms roughness. As we can see from transmission electron microscopy (TEM), this promotes the growth of smaller and fractured features in the initial stages of ITO growth. Furthermore, secondary ion mass spectrometry profiles show different penetration depths of hydrogen from the thin film silicon layers into the ITO, which might both influence ITO and device passivation properties. Comparing ITO to aluminum doped zinc oxide (AZO), we find that AZO can actually exhibit superior properties on nc-Si:H layers. We assess the impact of the modified ITO Rsh on the series resistance Rs of SHJ solar cells with >23% efficiency for optimized devices. This behavior should be considered when designing solar cells with amorphous or nanocrystalline layers as carrier selective contacts.
关键词： secondary ion mass spectrometry (SIMS),indium tin oxide (ITO),series resistance,Aluminum doped zinc oxide (AZO),transparent conductive oxide (TCO),transmission electron microscopy (TEM),silicon heterojunction (SHJ)
更新于2025-09-16 10:30:52
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Power Losses in the Front Transparent Conductive Oxide Layer of Silicon Heterojunction Solar Cells: Design Guide for Single-Junction and Four-Terminal Tandem Applications
摘要： In silicon heterojunction solar cells, optimization of the front transparent conductive oxide (TCO) layer is required in order to minimize both electrical and optical losses. In this article, design guidelines for this overall power loss minimization are presented—extending previous TCO optimization work that was limited to the maximization of the short-circuit current density alone—and these are used to prescribe the best TCOs for both single-junction and silicon-based four-terminal tandem applications. The employed procedure determines the loss associated with the front TCO layer as a function of the TCO carrier density, mobility, and thickness, as well as the pitch between the front electrode fingers. For a representative indium tin oxide (ITO) film with a mobility of approximately 20 cm2·V?1·s?1 and a carrier density of 2.5 × 1020 cm?3, the loss over the 700–1200 nm infrared wavelength range—the spectrum reaching the silicon bottom cell in a typical tandem structure—is minimized by using a finger pitch of 3 mm and an ITO thickness of 100–110 nm. This compares with an optimal finger pitch of 2 mm and an optimal ITO thickness of 70 nm for the same cell operating as a single-junction device under full spectrum. The methodology presented can also readily be applied to TCO materials other than ITO, to a wide variety of specific four-terminal tandem architectures and, with minor modifications, to rear TCO layers.
关键词： infrared (IR) spectrum,tandem solar cells,silicon heterojunction (SHJ) solar cells,transparent conductive oxide (TCO),Four-terminal
更新于2025-09-16 10:30:52
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[IEEE 2018 IEEE Photonics Conference (IPC) - Reston, VA, USA (2018.9.30-2018.10.4)] 2018 IEEE Photonics Conference (IPC) - Dual-Mode Silicon Photonic Crystal Nanocavity Modulator with Indium Oxide Gate
摘要： We report an ultra-efficient indium oxide gated silicon photonic crystal nanocavity electro-optical modulator, which is based on a dual-mode operation of resonance tuning and electro-absorption. With only 0.35μm long electrode, we achieved a tuning efficiency of 250pm/V and a modulation strength of 4dB/V with 35% from electro-absorption.
关键词： silicon photonics,modulator,photonic crystal cavity,transparent conductive oxide
更新于2025-09-09 09:28:46