Zoltan J. Kiss

A hybrid amorphous silicon photovoltaic and thermal solar collector

A hybrid amorphous silicon (a-Si) photovoltaic and thermal solar collector was developed and its performance tested. The solar cells, deposited on glass panels and having an average efficiency of 4% and a total area of 0.9 m2, were bonded to the fin and tube aluminum heat-exchange plate using simple technology. This hybrid unit performed well as a thermal solar collector, heating water up to 65°C, while the electric characteristics of the photovoltaic modules showed little change. In addition to saving space this integral unit substantially reduces the balance-of-system cost of the photovoltaic generator. The transmission of light through various layers of an a-Si cell was measured and, in order to improve the thermal efficiency, a novel transparent type of a-Si cell was developed and tested in the hybrid unit. The results obtained show that it is possible to construct simple and cheap hybrid systems having good photovoltaic as well as thermal efficiencies.

Polyacetylene, (CH)x: Photoelectrochemical solar cell

Photoelectrochemical photovoltaic cells have been fabricated using polyacetylene, (CH)x, as the active photoelectrode. Using a sodium polysulfide solution as electrolyte, Voc∼0.3 V and Isc∼40 μA/cm2 were obtained under illumination of approximately 1 sun. Under present conditions, the cell efficiency is limited by the series resistance, the small effective area of the electrode configuration, and the absorbance of the solution.Photoelectrochemical photovoltaic cells have been fabricated using polyacetylene, (CH)x, as the active photoelectrode. Using a sodium polysulfide solution as electrolyte, Voc∼0.3 V and Isc∼40 μA/cm2 were obtained under illumination of approximately 1 sun. Under present conditions, the cell efficiency is limited by the series resistance, the small effective area of the electrode configuration, and the absorbance of the solution.

A polyacetylene:aluminum photodiode

The fabrication of a 1‐cm2 (CH)x:Al Schottky photodiode with junction internal conversion efficiency of 0.30% and quantum efficiency approaching unity (hn≳2.8 eV) is reported. Device characteristics are presented. The effect of oxygen contamination is also discussed.

Preparation of amorphous silicon films by chemical vapor deposition from higher silanes SinH2n+2(n≳1)

Amorphous silicon films have been prepared by chemical vapor deposition from higher silanes Sin H2n+2 (n≳1) in the temperature range 380–500 °C. The films show electrical properties comparable to those prepared by the plasma discharge of silanes. Gold Schottky devices were fabricated with internal short‐circuit currents of 12 mA/cm2 under AM1 illumination over an area of 2.0 cm2.

Crystal Field Splitting in CaF2:Nd3+

The crystal field split levels of the 4I9/2 and 4I11/2 states of CaF2:Nd3+ were determined from the fluorescence and absorption spectra. The data are compared to an energy‐level calculation for the case of a weak cubic field containing fourth‐ and sixth‐order terms. Both the absorption and fluorescence spectra were found to be strongly concentration dependent at relatively low concentrations (0.01 mole %).

Photochromic materials for quantum electronics

The characteristics of idealized photochromic materials are defined. The optical properties of rare-earth-doped CaF 2 and transition-metal-doped SrTiO 3 photochromic materials are outlined. The operational parameters of these inorganic photochromic materials pertinent to electrooptic applications are described.

Optical and EPR studies of photochromic SrTiO 3 doped with Fe:Mo and Ni:Mo

Large reversible photochromic changes were observed in SrTiO 3 double doped with Mo and either Fe or Ni. The photochromic absorption is induced by irradiation in the vicinity of 4000 A and decays thermally in minutes or can be bleached to its original state by long wavelength radiation. A model is presented in which a charge is transferred between the Fe and Mo ions via the conduction or valence bands. Optical absorption, heat treatment, and EPR data are presented, which support the model.

PHOTO‐REVERSIBLE CHARGE TRANSFER IN RARE‐EARTH‐DOPED‐CaF2

Photoreversible absorption changes have been found in additively colored La‐, Ce‐, Gd‐, or Tb‐ doped CaF2. Results are shown for one of these, Ce:CaF2, in which both the trivalent and divalent rare‐earth absorptions are identifiable. These results suggest a charge transfer between the rare earth and a defect center produced by additive coloration.

Advances in large area CIGS technology

This paper describes results in several areas that, taken as a whole, significantly contribute to the advancement of CIGS PV technology based on vacuum deposition. These results include the large area sputtering of Mo suitable for very high efficiency cells, the improved delivery of Cu by linear source evaporation for large area vacuum deposition of CIGS, a promising non-Cd buffer layer capable of vacuum deposition, and improvement of the properties of doped ZnO.

Manufacturing process for interconnected submodules of hydrogenated amorphous silicon photovoltaic panels

Large scale deposition of hydrogenated amorphous silicon (a‐Si) for photovoltaic panels is discussed. The ‘‘box carrier’’ concept is introduced for hydrogenated a‐Si deposition. The spectral response studies prove that cross contamination is not present. Using this new concept, the average of 72 panels in one run is 5.6%. An I‐V curve for a square foot panel with an efficiency of 7.2% is shown. The utilization efficiency of silane is much higher (61%) than what has previously been reported (8%).