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Electron and proton irradiation effect on the minority carrier lifetime in SiC passivated p-doped Ge wafers for space photovoltaics
摘要： We report on the effect of electron and proton irradiation on effective minority carrier lifetimes (τeff) in p-type Ge wafers. Minority carrier lifetimes are assessed using the microwave-detected photoconductance decay (μW-PCD) method. We examine the dependence of τeff on the p-type doping level and on electron and proton radiation fluences at 1 MeV. The measured τeff before and after irradiation are used to estimate the minority carriers’ diffusion lengths, which is an important parameter for solar cell operation. We observe τeff ranging from ~50 to 230 μs for Ge doping levels between 1 × 1017 and 1 × 1016 at.cm-3, corresponding to diffusion lengths of ~500–1400 μm. A separation of τeff in Ge bulk lifetime and surface recombination velocity is conducted by irradiating Ge lifetime samples of different thicknesses. The possible radiation-induced defects are discussed on the basis of literature.
关键词： Space photovoltaics,Minority carrier lifetime,Germanium,Surface passivation,Irradiation
更新于2025-09-23 15:19:57
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The impact of interstitial Fe contamination on n-type Cz-Silicon for high efficiency solar cells
摘要： In this work, we have investigated the impact of interstitial Fe contamination on the effective minority carrier lifetime of n-type Cz silicon bulk material for high efficiency solar cells. The study covers a Fe concentration in the silicon bulk from 3.5 ? 1012 cm-3 to 2.7 ? 1014cm-3. We have added 5 different concentrations (30, 100, 300, 1000 and 3000 ppb) of Fe intentionally to a wet chemical process tank and measured the transfer to the silicon wafer surface mimicking a possible contamination during wet chemical processing. In order to fabricate carrier lifetime test vehicles, the silicon wafer is then passivated with thermal silicon oxide from both sides. The surface contamination is driven into the bulk by mimicking a high temperature process during solar cell manufacturing. Effective minority carrier lifetime is measured at injection levels from 1 ? 1013 cm-3 to 3 ? 1015cm-3. We have fitted the theoretical curve for interstitial Fe derived from the SRH theory to the measured values and extracted the Fe contamination concentration. This value is comparable to the calculated value extracted from the surface contamination measurement. For low level injection (LLI), we extracted the capture cross section for interstitial Fe to be 6.45 ? 10-17 cm/s ? 2.23 ? 10-17 cm/s. The measured Fe contamination levels are used for the conversion efficiency fitting of a n-type bifacial silicon solar cell using QUOKKA simulations. The simulations show that very low Fe contamination concentrations of [Fe]bulk ? 3.5 ? 1012 cm-3 ([Fe]surf ? 6 ? 1010cm-2) already degrade the solar cell efficiency by 10% relative.
关键词： Effective minority carrier lifetime,Interstitial Fe Contamination,QUOKKA simulations,n-type Si Solar cell,High efficiency
更新于2025-09-23 15:19:57
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Widening the 2D/3D Perovskite Family for Efficient and Thermal-Resistant Solar Cells by the Use of Secondary Ammonium Cations
摘要： While 2D/3D layered perovskites have been the object of comprehensive research principally focused on increasing the long-term stability observed in 3D perovskites, significant opportunities still exist concerning the application of different kinds of cations outside the sphere of primary amines, which are the cations most usually applied. Our results demonstrate that the materials and the solar cells prepared with dipropylammonium iodide (DipI), a bulky secondary ammonium cation of small size, lead to obtaining materials that are not only efficient and thermodynamically stable but also robust toward heat stress. Time-resolved studies indicate longer carrier lifetime for 2D/3D layered perovskites fabricated with this bulky cation than for systems based on bulky primary ammonium cations, which allowed us to obtain PCE = 12.51% (n = 10), 15.78% (n = 50), and 17.90% (n = 90). We determine that the concentration of perovskite material after 240 min at 100 °C is up to 575% greater in the 2D/3D perovskite (n = 10) than that observed in 3D perovskite films. The material stability also improves the thermal stability of the photovoltaic devices, presenting an efficiency drop of just 4% for n = 50 and n = 10 after thermal annealing while the performance drop for reference 3D samples in the same conditions was greater than 80%.
关键词： carrier lifetime,2D/3D perovskites,solar cells,thermal stability,secondary ammonium cations
更新于2025-09-19 17:13:59
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Performance analysis of narrow-bandgap interband cascade thermophotovoltaic cells
摘要： We present the detailed characterization and performance analysis of two sets of four interband cascade thermophotovoltaic (TPV) devices with InAs/GaSb type-II superlattice (SL) absorbers. The bandgaps of the SL absorbers in the four devices were between 0.22 and 0.25 eV at 300 K. With different numbers of cascade stages and individual absorber thicknesses, we are able to show how possible material quality variations and current mismatch between stages can affect the device performance. Based on the calculated effective quantum efficiency in each stage and experimental results, it is shown that the current mismatch between stages due to the deviation of absorption coefficient from the designed value can be substantial with more stages. On the other hand, the collection efficiency can be much improved with more stages and thin individual absorbers. Also, the carrier lifetime is extracted through measured dark current density to evaluate the material quality. The effects of material quality, current mismatch and collection efficiency on device performance are quantified and a comparison shows that material quality plays the most important role.
关键词： Interband cascade,current mismatch,carrier lifetime,thermophotovoltaic cells
更新于2025-09-19 17:13:59
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Built-in voltage enhanced by in-situ electrochemical polymerized undoped conjugated hole-transporting modifier in organic solar cells
摘要： Herein, a new electropolymerized (EP) film named poly-triphenylcarbazole fluoranthene (p-TPCF) has been in-situ synthesized by electrochemical cyclic voltammetry method, and applied to tune the work-function (WF) of the PEDOT:PSS hole-transporting layer (HTL) in organic solar cells (OSCs). Multi techniques, including Kelvin probe force microscopy (KPFM), light intensity dependent solar cell characterization, Mott-Schottky analysis, transient photovoltage (TPV) and transient photocurrent (TPC) measurements, have been explored to provide insights into the mechanism. Benefiting from deeper work-function (WF), larger built-in voltage (Vbi), decreased recombination, longer carrier lifetime, the devices with EP film exhibited superior device performance with simultaneously enhanced Voc, Jsc and FF.
关键词： PEDOT:PSS,built-in voltage,work-function tuning,organic solar cells,carrier lifetime,electropolymerized film,charge recombination
更新于2025-09-19 17:13:59
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Efficient defect passivation of perovskite solar cells via stitching organic bidentate molecule
摘要： The defects present in the solution-processed perovskite light absorbing materials are responsible for deteriorating the performance and stability of perovskite solar cells. Therefore, suppressing of the defect formation and passivating the pre-existing defects in perovskite materials is of paramount importance in pushing the efficiency of perovskite solar cell (PSC) toward the theoretical limit and ensuring the long-term stability of PSC. In this work, we report an efficient defect passivation route using a bidentate small organic molecule, pyrazine, which is capable of making either a monodentate or a bridging bidentate bonding with under-coordinated Pb2+ ions mainly present in the surface and grain-boundary of perovskite films. The various analyses for defect density and charge carrier lifetime of perovskite light absorbing layer demonstrated that the pyrazine effectively passivated defects existing on the surface and grain boundary of the perovskite films without affecting the morphology and crystallinity via a simple post-treatment procedure. As a result, the best untreated device obtained a power conversion efficiency of 19.14 %, while the efficiency of 20.58 % was achieved with pyrazine treated.
关键词： bidentate molecule,defect passivation,charge carrier lifetime,perovskite solar cells,pyrazine
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Control of Texture Size on As-Cut Crystalline Silicon by Microparticle-Assisted Texturing (MPAT) Process
摘要： The texture size on as-cut crystalline silicon (c-Si) is drastically reduced from ~22 μm to <2.7 μm when mixing glass microparticles with conventional alkaline texturing solutions. The processing time and c-Si loss are considerably reduced from >15 to ~3 min and from >8 to 2 μm (for one side), respectively. Thus, this process is applicable to very thin c-Si. High-quality surface passivation with the effective minority carrier lifetimes >7 ms, corresponding to surface recombination velocity of 0.38 cm/s was possible. After anti-reflection coating, the reflectivity ~0.4% at 600nm, and <2% in wide wavelength 450?950nm was achieved on this new texture.
关键词： photovoltaic cells,light trapping,charge carrier lifetime,etching,cleaning,silicon,chemical processes
更新于2025-09-19 17:13:59
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Effect of Si substrate modification on improving the crystalline quality, optical and electrical properties of thermally-evaporated BaSi2 thin-films for solar cell applications
摘要： We have grown orthorhombic barium disilicide (BaSi2) thin-films on modified silicon (Si) substrates by a thermal evaporation method. The surface modification of Si substrate was performed by a metal-assisted chemical etching method. The effects of etching time te on crystalline quality as well as optical and electrical properties of the BaSi2 films were investigated. The obtained results showed that substrate modification can enhance the crystalline quality and electrical properties; reduce the light reflection; and increase the absorption of the BaSi2 thin-films. The te of 8 s was chosen as the optimized condition for surface modification of Si substrate. The achieved inferred short-circuit current density, Hall mobility, and minority carrier lifetime of the BaSi2 film at te of 8 s were 38 mA/cm2, 273 cm2/Vs, and 2.3 μs, respectively. These results confirm that the BaSi2 thin-film evaporated on the modified Si substrate is a promising absorber for thin-film solar cell applications.
关键词： hall mobility,substrate modification,photoresponse,silicide semiconductor,Barium disilicide,minority carrier lifetime,optical property,thermal evaporation
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - In situ and ex situ Investigations of Oxygen, Light and Temperature Influence on Halide Perovskites: Absorption and Transport Properties
摘要： In this work multi-cations hybrid perovskite thin film properties were explored by characterization techniques that proved to be very powerful for inorganic thin films. In particular, we report the evolution of the ambipolar diffusion length under different environmental or thermal stresses by Steady State Photocarrier Grating, directly observing the effects of oxygen absorption/desorption onto the material electronic properties. Moreover, the effects of illumination on the absorption properties were investigated via Fourier Transform Photocurrent Spectroscopy, a technique that allows to access to weak absorptions (E<Eg).
关键词： charge carrier lifetime,photovoltaic cells,organic inorganic hybrid materials
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Photoluminescence Excitation Spectroscopy Characterization of Surface and Bulk Quality for Early-Stage Potential of Material Systems
摘要： Photoluminescence Excitation Spectroscopy (PLE) is a contactless characterization technique to quantify Shockley-Reed-Hall (SRH) lifetimes and recombination velocities in direct band gap experimental semiconductor materials and devices. It is also useful as to evaluate surface passivation and intermediate fabrication processes, since it can be implemented without the need for development of effective contact technologies. In this paper, we present a novel experimental PLE system for precision-based quantification of the aforementioned parameters as well as a system for which absolute PLE characterization may occur. Absolute PLE measurements can be used to directly calculate VOC for new photovoltaic (PV) material systems and devices. Key system capabilities include a continuous excitation spectrum from 300 nm –1.1 μm, automated characterization, up to 1 nm wavelength resolution (up to 60x higher than prior work), and a reduced ellipsometry requirement for post-processing of data. We utilize a GaAs double heterostructure (DH) and an InP crystalline wafer as calibration standards in comparison with data from an LED-based PLE to demonstrate the validity of the results obtained from this new system.
关键词： photovoltaic cells,indium phosphide,charge carrier lifetime,gallium arsenide,photoluminescence
更新于2025-09-19 17:13:59