Solar spectral irradiance blurring in the focal plane of the Fresnel lens arising from the chromatic aberration (CA) inherent to a lens was studied. The experimental complex for recording both ...irradiance distribution and spectral irradiance redistribution for the radiation concentrated by a small-sized energy concentrator based on a solar simulator with the possibility of modeling the spectral composition of light is presented. The methodology for scanning the irradiance spectral redistribution by a fiber spectrometer is described.
Schematic diagram of the bifacial silicon solar cell LGCell with ITO/p+(n or p)n+)Cz–Si/IFO structure processed in this work. Display omitted
•n-Type and p-type Cz-Si solar cells were fabricated on ...the basis of Ag-free LGCell design.•Application of TCO films and wire contact gridlines allowed decreasing the series resistance.•The LGCells are bifacial (bifaciality is 80–95%), low-concentrator (1–5X) devices.•Solar cells from p-Si showed front/rear efficiencies of 18.6–19.0%/14.9–15.3% at 1–5 suns.•Solar cells from n-Si showed front/rear efficiencies of 17.3–17.7%/18.1–18.5% at 1–5 suns.
Results obtained for the bifacial low concentrator Ag free Cz silicon solar cells based on Indium–Tin–Oxide(ITO)/(p+nn+)Cz–Si/Indium–Fluorine–Oxide (IFO) structure (“n-type” cell) as well as on IFO/(n+pp+)Cz–Si/ITO structure (“p-type” cell) are presented in this work. The (p+nn+)Cz–Si and (n+pp+)Cz–Si structures were produced by diffusion of boron and phosphorus from deposited B- and P-containing glasses followed by an etch-back step. The n+ surface of the structures was textured, whereas the p+ surface remained planar. Transparent Conducting Oxide (TCO) films, which act as antireflection electrodes, were deposited by ultrasonic spray pyrolysis method on both sides. The contact pattern of copper wire was attached by the low-temperature (160°C) lamination method simultaneously to the front and rear TCO layers as well as to the interconnecting ribbons arranged outside the structure. The shadowing from the contacts is in the range of ∼4%. The resulting solar cells showed front/rear efficiencies of 18.6–19.0%/14.9–15.3% (“p-type” cell) and 17.3–17.7%/18.1–18.5% (“n-type” cell) respectively at 1–5 suns. At 20–50% albedo of 1-sun illumination, similar energy production corresponds to 21.6–26.8% (n-type cell) and 21.6–26.1% (“p-type” cell) efficiency of a monofacial cell.
The temperature dependences of the diffusion and recombination saturation currents and the energy gap have been obtained for a GaAs photoelectric converters. Saturation currents by IV characteristic ...analysis, and the energy gap by electroluminescence peak position have been determined. It has been shown that the relationship between saturation currents and energy band gap is characterized by the only parameter Jz (current invariant). At the temperature range of 100 -420 K this parameter does not depend on the temperature.
"Solar" Abbe number is proposed to operate in assessing the suitability of optical materials at sunlight concentrators manufacture. Comparative results are presented for materials practically used in ...concentrator photovoltaics from the point of view of designing Fresnel lenses from them with a high average concentration in the focal spot of the minimum size and at the same time with minimum focal length.
The paper is devoted to the relationship between the energy gap and the saturation currents (diffusion and recombination ones) of GaInAs homo p-n junctions. Such a relationship is required for ...developing multi-junction solar cells and photodetectors for a given wavelength. The saturation currents and the energy gap have been determined experimentally, and an empirical exponential formula was obtained for the required relationship. The results of the work allow predicting the saturation current for a GaInAs p-n junction with a given energy gap.
Developed and investigated are IR (850 nm) light-emitting diodes based on AlGaAs/Ga(In)As heterostractures grown by the MOCVD technique with multiple quantum wells in the active region and with a ...double optical reflector consisted of a multilayer Al
0.9
Ga
0.1
As/Al
0.1
Ga
0.9
As Bragg heterostructure and an Ag mirror layer. Light-emitting diodes with the external quantum efficiency EQE = 37.5% at current densities greater than >10 A/cm
2
have been fabricated.
GalnP-based laser power converters (LPC) structure grown by MOVPE and device chip design have been optimized for operation under high-power lasers of the green–red spectral range. Light
I–V
curves ...records have shown the performance of the LPC at up to 40–50 W/cm
2
of incident power densities. The highest level data were obtained for 532, 600, and 633 nm power laser lines: 44.3, 46.7, and 40.6% under 13–16 W/cm
2
, respectively. LPC demonstrated an efficiency of more than 40% at the incident laser radiation power density elevated up to 40–50 W/cm
2
.
The efficiency of GaInP/GaAs/In
x
Ga
1 –
x
As triple-junction solar cells obtained by replacing (in the widely used “classical” GaInP/GaAs/Ge heterostructure) the lower germanium with In
x
Ga
1 –
x
...As subcell formed using the metamorphic growth technology has been investigated. Based on an original approach, the optimal indium concentration in the narrow-gap subcell has been found. The main parameters of In
x
Ga
1 –
x
As subcells with an indium concentration from
x
=
0.11 to 0.36 were determined and were used to calculate the IV characteristics of GaInP/GaAs/In
x
Ga
1 –
x
As solar cells. It has been determined that at
x
=
0.28 the efficiency of the triple-junction solar cell increases by 3.4% (abs.) in comparison with the “classical” solar cell, reaching a value of 40.3% (AM1.5D). Also it has been shown that the efficiency of such solar cells can be increased up to 41%.
Optimized photoconverters for operation under high-power laser radiation in the green-red spectral range based on MOCVD-grown GaInP/GaAs heterostructures are fabricated. The Au(Ge)/Ni/Au and Pd/Ge/Au ...contact systems have been studied to form the front contact grid of devices. As a result, the laser photoconverter with a Pd/Ge/Au contact showed an efficiency of more than 50% up to an incident radiation power density of 30 W/cm
2
with a maximum value of 54.4% under 7 W/cm
2
for laser line with wavelength of 600 nm.
The “top” intergenerator part situated between the GaInP and GaAs subcells (electric power generators) is analyzed. The shape of the light current–voltage characteristics and the
V
oc
–
J
sc
...(open-circuit voltage–short-circuit current) dependence are examined. It is found that the
p
+
–
n
+
tunnel heterojunction situated in the “top” intergenerator part can operate as a photoelectric source counteracting the base
p
–
n
junctions. In this case, the
V
oc
–
J
sc
characteristic has a descending part, and a sharp jump can be observed. This undesirable effect becomes weaker with increasing peak current of the tunnel junction.
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