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Presents calculations of the effective shading of metal fingers taking light trapping in the encapsulant into account and provides experimental data in support of the calculations. Trapping of light reflected from metal fingers; Experimental details; Discussion on the grid design.

Presents a study which described the optical and electrical characterization of high-efficiency silicon solar cells. Method of the study; Results and discussion; Conclusion.

Evaluates the experimental bounds on band-gap narrowing set by high open circuit voltage silicon solar cells. Constraints upon the magnitude of such band-gap narrowing; Properties of the substrate of metal-insulator-n-type-p-type (MINP) solar cells; Properties of the emitter of MINP solar cells; Details of a numerical analysis of MINP solar cell emitters.

The luminescence properties of pyrene ethenes, both as monomer and aggregate species, are found to depend on the regioisomer structure. Systematic shifts in absorption, emission, and excitation spectra of the gem-pyrene ethenes, both in solution and in rigid polymer hosts, are consistent with weakly interacting H-aggregate formation. This aggregation leads to excimer-like emission with Stokes shifts greater than 1 eV. Planar concentrators fabricated from gem-pyrene diphenylethenes show comparable performance to previously reported inorganic phosphors. The UV absorption and emission properties of the planar concentrator devices exhibit potential for transparent solar concentrators or visible-blind photodetector applications. This is the first demonstration of exploiting the unusual photophysics of molecular aggregates in planar concentrators. [ABSTRACT FROM AUTHOR]

ABSTRACT The series resistance ( Rs) of a solar cell is commonly represented as a constant resistance value. However, because of the distributed nature of series resistance, the effective lumped Rs vary with current density and illumination intensity. Treating Rs as a constant is usually insufficient for an accurate analysis of its J-V curve. This work first presents a review of the distributed nature of series resistance and commonly applied methods to measure Rs. Particular attention is given to the multi-light method (MLM) and it is discussed in detail, where Rs in both the light and dark can be measured as a function of current by extracting Rs from a set of current-voltage ( J-V) curves attained at different illumination intensities. The principle behind this method is discussed, and the results are then compared with those of other known methods of Rs measurement. The accurate measurement of Rs( J) attained with the MLM permits the extraction of an Rs-corrected J-V curve, which is theoretically more accurate than that attained by alternative methods because of negligible error from injection dependence and spectral mismatch. With the solar cell equation modified to include Rs( J), we attain a much better fit to experimental data, finding a significant reduction in error compared with using a constant Rs. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The bonded hydrogen concentration in thermally annealed low-pressure chemical vapor deposition (LPCVD) Si3N4 films increases rapidly following exposure to ammonia plasma and saturates at a concentration determined by the thermal history of the films. Where the nitride layer is deposited on oxidized silicon samples, the introduction of hydrogen into the nitride film using ammonia plasma is effective at passivating the Si-SiO2 interface. The plasma treatment does not lead to the generation of a significant number of additional interface defects, shown by lifetime and electronic paramagnetic resonance measurements. Subsequent anneals in nitrogen further improve the interface passivation. [ABSTRACT FROM AUTHOR]

Using a combination of etch rate, photoconductance, and deep level transient spectroscopy (DLTS) measurements, the authors have investigated the use of reactive ion etching (RIE) of dielectrics and Si in CHF3/O2 and CHF3/Ar plasmas for photovoltaic applications. The radio frequency power (rf-power) and gas flow rate dependencies have shown that the addition of either O2 or Ar to CHF3 can be used effectively to change the etch selectivity between SiO2 and Si3N4. The effective carrier lifetime of samples degraded upon exposure to a CHF3-based plasma, reflecting the introduction of recombination centers in the near-surface region. The extent of minority carrier lifetime degradation was similar in both types of plasmas, suggesting that the same defects were responsible for the increased recombination. However, the rf-power dependence of lifetime degradation in n- and p-type Si was different. Moreover, the lifetime degradation did not exhibit a linear rf-power dependence, suggesting that primary defects were not the dominant recombination centers responsible for the decrease in lifetime. Indeed, DLTS measurements have shown that secondary defects were formed in samples exposed to the plasma after annealing at 400 °C, the temperature at which a SiN:H layer is deposited on samples to passivate their surfaces. The minority carrier lifetime degradation in RIE processed samples could be partially avoided using post-RIE chemical treatments. [ABSTRACT FROM AUTHOR]

Further improvements in crystalline silicon solar cell performance have been obtained by combining the high levels of surface recombination control demonstrated in earlier passivated emitter solar cells with an improved optical approach. This approach involves the use of microgrooved surfaces which retain the advantages of pyramidally textured surfaces while avoiding some disadvantages of the latter. The approach results in a 5–6% improvement in cell short-circuit current density for cells fabricated on 0.1 and 0.2 Ω cm ( p type) substrates. This results in an energy conversion efficiency for these devices above 20% under standard terrestrial test conditions (AM1.5, 100 mW/cm2) for the first time. [ABSTRACT FROM AUTHOR]

Several recent high performance silicon solar cells have taken advantage of surface oxide passivation to improve both their short wavelength response and open-circuit voltage. Using low resistivity substrates to minimize base recombination rates, the effect of oxidation conditions upon the passifying properties of thin oxides is quantified. It is shown that emitter recombination in high efficiency cells decreases by a factor of at least 3 and most probably 7 as the oxide growth temperature increases from 825 to 900 °C and the oxide thickness increases from 60 to 100 Å. This increase in performance is at the expense of a slight loss in cell short-circuit current density. [ABSTRACT FROM AUTHOR]