A program continuation to develop processing procedures for advanced silicon solar cells

Shallow junctions, aluminum back surface fields and tantalum pentoxide (Ta205) antireflection coatings coupled with the development of a chromium-palladium-silver contact system, were used to produce a 2 x 4 cm wraparound contact silicon solar cell. One thousand cells were successfully fabricated using batch processing techniques. These cells were 0.020 mm thick, with the majority (800) made from nominal ten ohm-cm silicon and the remainder from nominal 30 ohm-cm material. Unfiltered, these cells delivered a minimum AMO efficiency at 25 C of 11.5 percent and successfully passed all the normal in-process and acceptance tests required for space flight cells

Effect of dopants on annealing performance of silicon solar cells

The optimum annealing parameters of time and temperature for producing cell output recovery were established. Devices made from gallium doped and boron doped silicon were investigated. The cells ranged in resistivity from 0.1 to 20 ohm-cm and in thickness from 50 to 250 micrometers. The observations can be explained in a qualitative manner by postulating a pair of competing mechanisms to account for the low temperature reverse annealing seen in most boron and gallium doped silicon solar cells. Still another mechanism dominates at higher temperatures (350 C and greater) to complete this model. One of the mechanisms, defined as B, allows migrators to couple with radiation induced recombination sites thus increasing or enhancing their capture cross sections. This would tend to reduce minority carrier diffusion length. The new recombination complex is postulated to be thermally stable up to temperatures of approximately 350 C

Design and fabrication of wraparound contact silicon solar cells

Both dielectric insulation and etched junction contact techniques were evaluated for use in wraparound contact cell fabrication. Since a suitable process for depositing the dielectrics was not achieved, the latter approach was taken. The relationship between loss of back contact and power degradation due to increased series resistance was established and used to design a simple contact configuration for 10 ohm-cm etched wraparound junction contact N/P cells. A slightly deeper junction significantly improved cell curve shape and the associated loss of current was regained by using thinner contact grid fingers. One thousand cells with efficiencies greater than 10.5% were fabricated to demonstrate the process

Development of processing procedures for advanced silicon solar cells

Ten ohm-cm silicon solar cells, 0.2 mm thick, were produced with short circuit current efficiencies up to thirteen percent and using a combination of recent technical advances. The cells were fabricated in conventional and wraparound contact configurations. Improvement in cell collection efficiency from both the short and long wavelengths region of the solar spectrum was obtained by coupling a shallow junction and an optically transparent antireflection coating with back surface field technology. Both boron diffusion and aluminum alloying techniques were evaluated for forming back surface field cells. The latter method is less complicated and is compatible with wraparound cell processing

Electron irradiation of tandem junction solar cells

The electrical behavior of 100 micron thick tandem junction solar cells manufactured by Texas Instruments was studied as a function of 1 MeV electron fluence, photon irradiation, and 60 C annealing. These cells are found to degrade rapidly with radiation, the most serious loss occurring in the blue end of the cell's spectral response. No photon degradation was found to occur, but the cells did anneal a small amount at 60 C

Single-channel properties of a stretch-sensitive chloride channel in the human mast cell line HMC-1

A stretch-activated (SA) Cl− channel in the plasma membrane of the human mast cell line HMC-1 was identified in outside-out patch-clamp experiments. SA currents, induced by pressure applied to the pipette, exhibited voltage dependence with strong outward rectification (55.1 pS at +100 mV and an about tenfold lower conductance at −100 mV). The probability of the SA channel being open (Po) also showed steep outward rectification and pressure dependence. The open-time distribution was fitted with three components with time constants of τ1o = 755.1 ms, τ2o = 166.4 ms, and τ3o = 16.5 ms at +60 mV. The closed-time distribution also required three components with time constants of τ1c = 661.6 ms, τ2c = 253.2 ms, and τ3c = 5.6 ms at +60 mV. Lowering extracellular Cl− concentration reduced the conductance, shifted the reversal potential toward chloride reversal potential, and decreased the Po at positive potentials. The SA Cl− currents were reversibly blocked by the chloride channel blocker 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS) but not by (Z)-1-(p-dimethylaminoethoxyphenyl)-1,2-diphenyl-1-butene (tamoxifen). Furthermore, in HMC-1 cells swelling due to osmotic stress, DIDS could inhibit the increase in intracellular [Ca2+] and degranulation. We conclude that in the HMC-1 cell line, the SA outward currents are mediated by Cl− influx. The SA Cl− channel might contribute to mast cell degranulation caused by mechanical stimuli or accelerate membrane fusion during the degranulation process

Sheddable Coatings for Long-Circulating Nanoparticles

Nanoparticles, such as liposomes, polymeric micelles, lipoplexes and polyplexes are frequently studied as targeted drug carrier systems. The ability of these particles to circulate in the bloodstream for a prolonged period of time is often a prerequisite for successful targeted delivery. To achieve this, hydrophilic ‘stealth’ polymers, such as poly(ethylene glycol) (PEG), are used as coating materials. Such polymers shield the particle surface and thereby reduce opsonization by blood proteins and uptake by macrophages of the mononuclear phagocyte system. Yet, after localizing in the pathological site, nanoparticles should deliver their contents in an efficient manner to achieve a sufficient therapeutic response. The polymer coating, however, may hinder drug release and target cell interaction and can therefore be an obstacle in the realization of the therapeutic response. Attempts have been made to enhance the therapeutic efficacy of sterically stabilized nanoparticles by means of shedding, i.e. a loss of the coating after arrival at the target site. Such an ‘unmasking’ process may facilitate drug release and/or target cell interaction processes. This review presents an overview of the literature regarding different shedding strategies that have been investigated for the preparation of sterically stabilized nanoparticulates. Detach mechanisms and stimuli that have been used are described

Business networks and localization effects for new Swedish technology-based firms’ innovation performance

This study examines the business networks and localization effects for new technology-based firms (NTBFs) in the context of innovation performance (the number of patents and product differentiation). In this regard, the study includes 28 variables. A survey was conducted in 2016 with 401 Swedish NTBFs that were small and young (the employment mean was 1.80 and the average age of each firm was 28.3\ua0months). The biggest category of NTBFs was knowledge-intensive high-technology services, followed by medium high-technology manufacturing, and high-technology manufacturing. Hypotheses on how business networks and localization are related to innovation performance were tested using principal component analysis, correlation analysis, and regression analysis. The results show that the primary significant factor for innovation performance regarding business networks and localization dimensions are professional network services, while industrial and regional areas also have a positive relationship on product differentiation. Our study also shows that innovation performance enhances firms’ abilities to access external financing through professional network services (e.g., venture capital companies)