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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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Coexistence of quasi-CW and SBS-boosted self-Q-switched pulsing in ytterbium-doped fiber laser with low Q-factor cavity
摘要： As a key component in the wind turbine system, the power electronic converter and its power semiconductors suffer from complicated power loadings related to environment, and are proven to have high failure rates. Therefore, correct lifetime estimation of wind power converter is crucial for the reliability improvement and also for cost reduction of wind power technology. Unfortunately, the existing lifetime estimation methods for the power electronic converter are not yet suitable in the wind power application, because the comprehensive mission profiles are not well specified and included. Consequently, a relative more advanced approach is proposed in this paper, which is based on the loading and strength analysis of devices and takes into account different time constants of the thermal behaviors in power converter. With the established methods for loading and lifetime estimation for power devices, more detailed information of the lifetime-related performance in wind power converter can be obtained. Some experimental results are also included to validate the thermal behavior of power device under different mission profiles.
关键词： lifetime prediction,IGBT,power semiconductor device,thermal cycling,wind power,mission profiles
更新于2025-09-23 15:19:57
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Ice Confinement-Induced Solubilization and Aggregation of Cyanonaphthol Revealed by Fluorescence Spectroscopy and Lifetime Measurements
摘要： When an aqueous salt solution freezes, a freeze concentrated solution (FCS) separates from ice. The properties of the FCS may differ from those of a supercooled bulk solution of the same ionic strength at the same temperature. The fluorescence and lifetime characteristics of 6-cyano-2-naphthol (6CN) were studied in frozen NaCl solutions to provide an insight into the solution properties of the FCS. While the photoacidity of 6CN in an FCS is similar to that in solution, several anomalous behaviors are observed. Fluorescence spectra indicate that the solubility of 6CN is significantly enhanced in the FCS (50 mM or higher) compared to that in bulk NaCl solution, where the solubility limit is 250 μM. The high solubility induces aggregation of 6CN in the FCS, which is not detected in bulk solutions. This trend becomes marked as the initial NaCl concentration decreases, that is, the FCS is confined in a small space. The fluorescence lifetimes of 6CN in the FCS support the spectroscopy results. In addition to the species identified by fluorescence spectroscopy, excimers are assigned from lifetime measurements in the FCS. The excimer formation is also a result of the enhanced solubility of 6CN in the FCS.
关键词： solubility enhancement,aggregation,lifetime measurements,excimer formation,6-cyano-2-naphthol,freeze concentrated solution,Fluorescence spectroscopy
更新于2025-09-23 15:19:57
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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) - Ultra-thin LPCVD SiN <sub/>x</sub> /n+poly-Si passivated contacts a?? A possibility?
摘要： This work explores the possibility of using ultrathin silicon nitride (SiNx) films with high positive fixed charge in a SiNx/poly-Si passivating contact. The factors including (i) film thickness, (ii) annealing condition (time, temp and ambient) and (iii) surface pre-treatment were optimized to boost the passivation performance of ultrathin LPCVD SiNx films. Our preliminary experiments reveal excellent surface passivation and low recombination current density, Jo (45 fA.cm-2) by ~1.5 nm thick LPCVD SiNx films when subjected to an air ambient anneal at 800?C for 30 mins. This is due to the formation of high positive fixed charge density (1.5 ?10 12 cm-2). Air ambient annealed (465 μs) samples also have a higher lifetime when compared to the forming gas annealed (208 μs) samples. These passivating SiNx films were further integrated into SiNx/n+poly-Si contacts and characterized for Jo,contact and tunneling resistance, ?contact. The best SiNx/n+poly-Si passivated contact in this study has Jo, contact = 5.9 fA.cm-2, ?contact = 0.525 Ω.cm2 and an efficiency potential > 22.75%. According to our knowledge, it is the first report confirming the formation of passivated contacts with SiNx as the dielectric tunnel layer.
关键词： poly-Si,TEM,LPCVD SiNx,annealing,lifetime studies,passivated contact,silicon nitride,tunnel layer
更新于2025-09-23 15:19:57
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Investigation of spontaneous emission dynamics of dye molecules coupled into transverse Anderson localized cavities in a hyperbolic waveguide
摘要： Spontaneous emission dynamics of rhodamine 6G molecules coupled into transverse Anderson localized modes in a hyperbolic waveguide is investigated using time-resolved experiments. Four hyperbolic waveguides are simultaneously formed inside a deltoid-shaped fused-silica microtube via the capillary effect. The disordered photonic environment consisting of a rhodamine-doped polymeric material with randomly distributed air inclusions is attributed to localize photons at various resonant wavelengths of the quasi-optical cavities, randomly positioned throughout the guiding medium. The hyperbolic waveguides allow obtaining a single, double, and multimode resonant structures, trapping photons at various frequencies as explored in the form of sharp spectral resonances within the photoluminescence spectrum bandwidth of the dye molecules. Experimental results reveal that the coupling of the fluorescent emitters into multimode localizations in each hyperbolic waveguide corresponds to obtaining quasi-optical cavities at various resonant frequencies, which alter the emission characteristics of the emitters distinctively. The spontaneous emission rate of the dye molecules coupled into the isolated transverse Anderson localized modes is observed to increase by a factor of up to 6.7; thus, the vacuum fluctuations at certain resonant wavelengths are considerably enhanced.
关键词： Spontaneous emission,Transverse Anderson localization,Optical mode,Nano-cavity,Fluorescence lifetime
更新于2025-09-23 15:19:57
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[IEEE 2019 Chinese Automation Congress (CAC) - Hangzhou, China (2019.11.22-2019.11.24)] 2019 Chinese Automation Congress (CAC) - A New Method for Multiple Open-Transistor Fault Diagnosis in Photovoltaic micro-grid inverter by disposing the output current
摘要： If there is no reactive power exchange between a doubly fed induction generator (DFIG) and a grid, the various characteristics of the power converters in a DFIG wind turbine system cause the lifetime expectancy of a rotor-side converter (RSC) to be significantly less than that of a grid-side converter (GSC). In order to fulfill modern grid codes, over-excited reactive power injection will further reduce the lifetime of the RSC. In this paper, the additional stress of a power semiconductor due to the reactive power injection is first evaluated in terms of a modulation index and the current loading. Then, an optimized reactive power flow is proposed in the case where an over-excited reactive power support is applied with the joint compensation from both the RSC and the GSC. Finally, some experimental validations are performed at a downscale DFIG prototype. It is concluded that, among the different combined reactive power support strategies, the best scheme will tradeoff the lifetime between the GSC and the RSC.
关键词： thermal behavior,Consumed lifetime,reactive power,doubly fed induction generator (DFIG)
更新于2025-09-23 15:19:57
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[IEEE 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Berlin, Germany (2019.6.23-2019.6.27)] 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Manipulation of Biomolecules Into Nanogap by Plasmonic Optical Excitation for Highly Sensitive Biosensing
摘要： This paper presents an apparatus and methodology for an advanced accelerated power cycling test of insulated-gate bipolar transistor (IGBT) modules. In this test, the accelerated power cycling test can be performed under more realistic electrical operating conditions with online wear-out monitoring of tested power IGBT module. The various realistic electrical operating conditions close to real three-phase converter applications can be achieved by the simple control method. Further, by the proposed concept of applying the temperature stress, it is possible to apply various magnitudes of temperature swing in a short cycle period and to change the temperature cycle period easily. Thanks to a short temperature cycle period, test results can be obtained in a reasonable test time. A detailed explanation of apparatus such as configuration and control methods for the different functions of accelerated power cycling test setup is given. Then, an improved in situ junction temperature estimation method using on-state collector–emitter voltage VC E O N and load current is proposed. In addition, a procedure of advanced accelerated power cycling test and test results with 600 V, 30 A transfer molded IGBT modules are presented in order to verify the validity and effectiveness of the proposed apparatus and methodology. Finally, physics-of-failure analysis of tested IGBT modules is provided.
关键词： insulated-gate bipolar transistor module,physics-of-failure,power cycling test,lifetime model,Failure mechanism,reliability
更新于2025-09-23 15:19:57
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A negative polaron resistant p-type host for extended lifetime in deep blue phosphorescent organic light-emitting diodes
摘要： A novel mixed host employing a negative polaron stabilizing p-type host was developed to extend the device lifetime of blue phosphorescent organic light-emitting diodes (PhOLEDs). Instead of a conventional p-type host with only a hole transport unit, a p-type host with a negative polaron resistant unit in addition to the hole transport unit was used in the mixed host consisting of a p-type host and an n-type host. The p-type host had benzonitrile as a negative polaron resistant unit which stabilized the molecule under negative polarons. The use of the p-type host with the benzonitrile unit almost doubled the device lifetime of the blue PhOLEDs due to the improved negative polaron stability of the hosts. Therefore, the p-type host with the weak electron accepting benzonitrile unit can play the role of a lifetime extending p-type host to replace a conventional p-type host.
关键词： p-type host,device lifetime,negative polaron,benzonitrile,blue phosphorescent organic light-emitting diodes
更新于2025-09-23 15:19:57
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Benzonitrile and dicyanocarbazole derived electron transport type host materials for improved device lifetime in blue thermally activated delayed fluorescent organic light-emitting diodes
摘要： Three electron transport type host materials, 1DBF-2CNCZ, 2DBF-2CNCZ and 4DBF-2CNCZ, for blue thermally activated delayed fluorescent (TADF) organic light-emitting diodes (OLEDs) were synthesized and characterized. The host materials shared a dibenzofuran, benzonitrile and dicyanocarbazole units as the electron transport moieties, and had an isomeric molecular structure with different substitution positions of the dibenzofuran moiety. They showed high triplet energy above 3.0 eV by a twisted molecular structure and were applied as the electron transport type hosts in the mixed host system with a hole transport type mCBP host for blue TADF OLEDs. The blue TADF OLEDs developed using the 1DBF-2CNCZ host demonstrated high EQE over 20% and 31 h lifetime up to 75% of initial luminance at 500 cd/m2 at a mixed host composition of mCBP:1DBF-2CNCZ (25:75).
关键词： mixed host,efficiency,TADF,device lifetime,electron transport type host
更新于2025-09-23 15:19:57
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A perspective on blue TADF materials based on carbazole-benzonitrile derivatives for efficient and stable OLEDs
摘要： The advent of materials with thermally activated delayed ?uorescence (TADF) has triggered a wave of research to break the mutual exclusion of high ef?ciency and long lifetime of blue organic light-emitting diodes. Representatively, multiple donor-acceptor-type carbazole-benzonitrile (CzBN) derivatives have realized the longest device lifetimes in the blue region up to now together with high ef?ciencies among all TADF emitters. This perspective timely summarizes the progress of molecular design and device performances of CzBN derivatives and is concluded by providing suggestions on the future development of such materials and the corresponding devices.
关键词： OLEDs,high efficiency,carbazole-benzonitrile derivatives,long lifetime,blue TADF materials
更新于2025-09-23 15:19:57