In 2006, around 86% of all wafer-based silicon solar cells were produced using screen printing to form the silver front and aluminium rear contacts and chemical vapour deposition to grow silicon nitride as the antireflection coating onto the front surface. This paper reviews this dominant solar cell technology looking into state-of-the-art equipment and corresponding processes for each process step. The main efficiency losses of this type of solar cell are analyzed to demonstrate the future efficiency potential of this technology. In research and development, more various advanced solar cell concepts have demonstrated higher efficiencies. The question which arises is &#8220;why are new solar cell concepts not transferred into industrial production more frequently?&#8221;. We look into the requirements a new solar cell technology has to fulfill to have an advantage over the current approach. Finally, we give an overview of high-efficiency concepts which have already been transferred into industrial production.

Dirk-Holger Neuhaus

Adolf M&#252;nzer

Industrial Silicon Wafer Solar Cells

Armin Aberle

Recent Advances in Solar Cells

The low-cost chemical bath deposition (CBD) technique is used to prepare CBD-ZnS films as antireflective (AR) coating for multicrystalline silicon solar cells. The uniformity of CBD-ZnS film on large area of textured multicrystalline silicon surface is the major challenge of CBD technique. In the present work, attempts have been made for the first time to improve the rate of deposition and uniformity of deposited film by controlling film stoichiometry and refractive index and also to minimize reflection loss by proper optimization of molar percentage of different chemical constituents and deposition conditions. Reasonable values of film deposition rate 
 (12.13 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover><mml:mrow><mml:mtext>&#x000C5;</mml:mtext></mml:mrow><mml:mrow><mml:mi>&#x02032;</mml:mi></mml:mrow></mml:mover></mml:mrow></mml:math>/min.), good film uniformity (standard deviation <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>&#x003C;</mml:mo></mml:math>1), and refractive index (2.35) along with a low percentage of average reflection (6-7&#37;) on a textured mc-Si surface are achieved with proper optimization of ZnS bath. 12.24&#37; efficiency on large area (125&#x2009;mm <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>&#x00D7;</mml:mo></mml:math> 125&#x2009;mm) multicrystalline silicon solar cells with CBD-ZnS antireflection coating has been successfully fabricated. The viability of low-cost CBD-ZnS antireflection coating on large area multicrystalline silicon solar cell in the industrial production level is emphasized.

U. Gangopadhyay

K. Kim

S. K. Dhungel

H. Saha

J. Yi

Application of CBD-Zinc Sulfide Film as an Antireflection Coating on Very Large Area Multicrystalline Silicon Solar Cell

Solar cells based on organic semiconductors have attracted much attention. The thickness of the active layer of organic solar cells is typically only 100 nm thin, which is about 1000 times thinner than for crystalline silicon solar cells and still 10 times thinner than for current inorganic thin film cells. The low material consumption per area and the easy processing of organic semiconductors offer a huge potential for low cost large area solar cells. However, to compete with inorganic solar cells the efficiency of organic solar cells has to be improved by a factor of 2-3. Several organic semiconducting materials have been investigated so far, but the optimum material still has to be designed. Similar as for organic light emitting devices (OLED) small molecules are competing with polymers to become the material of choice. After a general introduction into the device structures and operational principles of organic solar cells the three different basic types (all polymer based, all small molecules based and small molecules mixed with polymers) are described in detail in this review. For each kind the current state of research is described and the best of class reported efficiencies are listed.

Thomas Kietzke

Recent Advances in Organic Solar Cells

The changes in open-circuit voltage (<mml:math id="E1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>V</mml:mi><mml:mrow><mml:mtext>o</mml:mtext><mml:mtext>c</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:math>), 
short-circuit current density (<mml:math id="E2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>J</mml:mi><mml:mrow><mml:mtext>s</mml:mtext><mml:mtext>c</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:math>), and
 internal quantum efficiency (IQE) of aLuminum induced crystallization, ion-assisted deposition (ALICIA) polycrystalline silicon thin-film solar cells on low-temperature glass substrates due to rapid thermal anneal (RTA) treatment and subsequent remote microwave hydrogen plasma passivation (hydrogenation) are examined.
 <mml:math id="E3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>V</mml:mi><mml:mrow><mml:mtext>o</mml:mtext><mml:mtext>c</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:math>
 improvements from 130&#x2009;mV to 430&#x2009;mV, <mml:math id="E4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>J</mml:mi><mml:mrow><mml:mtext>s</mml:mtext><mml:mtext>c</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:math>
 improvements from 1.2&#x2009;mA/cm2
 to 11.3&#x2009;mA/cm2, and peak IQE improvements from 
 16&#x25; to <mml:math id="E5" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>&#x003E;</mml:mo></mml:math> 70&#x25; are achieved. A 1-second RTA plateau at 1000&#xB0;C followed by hydrogenation increases the <mml:math id="E6" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>J</mml:mi><mml:mrow><mml:mtext>s</mml:mtext><mml:mtext>c</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:math> by a factor of 5.5. Secondary ion mass spectroscopy measurements are used to determine the concentration profiles of dopants, impurities, and hydrogen. Computer modeling based on simulations of the measured IQE data reveals that the minority carrier lifetime in the absorber region increases by 3 orders of magnitude to about 1 nanosecond (corresponding to a diffusion 
length of at least 1&#x2009;<mml:math id="E7" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>&#x03BC;</mml:mi></mml:math>m) due to RTA and subsequent hydrogenation. The evaluation of the changes in the quantum efficiency and <mml:math id="E8" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>V</mml:mi><mml:mrow><mml:mtext>o</mml:mtext><mml:mtext>c</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:math> due to RTA and hydrogenation with computer modeling significantly improves the understanding of the limiting factors to cell performance.

Mason L. Terry

Daniel Inns

Armin G. Aberle

Rapid Thermal Annealing and Hydrogen Passivation of Polycrystalline Silicon Thin-Film Solar Cells on Low-Temperature Glass

The high efficiency of multijunction concentrator cells has the potential to revolutionize the cost structure of photovoltaic electricity generation. Advances in the design of metamorphic subcells to reduce carrier recombination and increase voltage, wide-band-gap tunnel junctions capable of operating at high concentration, metamorphic buffers to transition from the substrate lattice constant to that of the epitaxial subcells, concentrator cell AR coating and grid design, and integration into 3-junction cells with current-matched subcells under the terrestrial spectrum have resulted in new heights in solar cell performance. A metamorphic 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mtext>Ga</mml:mtext></mml:mrow><mml:mrow><mml:mn>0</mml:mn><mml:mn>.44</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mtext>In</mml:mtext></mml:mrow><mml:mrow><mml:mn>0</mml:mn><mml:mn>.56</mml:mn></mml:mrow></mml:msub><mml:mtext>P</mml:mtext><mml:mo>/</mml:mo><mml:msub><mml:mrow><mml:mtext>Ga</mml:mtext></mml:mrow><mml:mrow><mml:mn>0.92</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mtext>In</mml:mtext></mml:mrow><mml:mrow><mml:mn>0.08</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>As/ Ge 3-junction solar cell from this research has reached a record 40.7&#37; efficiency at 240 suns, under the standard reporting spectrum for terrestrial concentrator cells (AM1.5 direct, low-AOD, 24.0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mrow><mml:mtext>W/cm</mml:mtext></mml:mrow><mml:mtext>2</mml:mtext></mml:msup></mml:mrow></mml:math>, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mrow><mml:mtext>25</mml:mtext></mml:mrow><mml:mo>&#x2218;</mml:mo></mml:msup><mml:mtext>C</mml:mtext></mml:mrow></mml:math>), and experimental lattice-matched 3-junction cells have now also achieved over 40&#37; efficiency, with 40.1&#37; measured at 135 suns. This metamorphic 3-junction device is the first solar cell to reach over 40&#37; in efficiency, and has the highest solar conversion efficiency for any type of photovoltaic cell developed to date. Solar cells with more junctions offer the potential for still higher efficiencies to be reached. Four-junction cells limited by radiative recombination can reach over 58&#37; in principle, and practical 4-junction cell efficiencies over 46&#37; are possible with the right combination of band gaps, taking into account series resistance and gridline shadowing. Many of the optimum band gaps for maximum energy conversion can be accessed with metamorphic semiconductor materials. The lower current in cells with 4 or more junctions, resulting in lower <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mi>I</mml:mi><mml:mi>2</mml:mi></mml:msup><mml:mi>R</mml:mi></mml:mrow></mml:math> resistive power loss, is a particularly significant advantage in concentrator PV systems. Prototype 4-junction terrestrial concentrator cells have been grown by metal-organic vapor-phase epitaxy, with preliminary measured efficiency of 35.7&#37; under the AM1.5 direct terrestrial solar spectrum at 256 suns.

Richard R. King

Daniel C. Law

Kenneth M. Edmondson

Christopher M. Fetzer

Geoffrey S. Kinsey

Hojun  Yoon

Dimitri D. Krut

James H. Ermer

Raed A. Sherif

Nasser H. Karam

Advances in High-Efficiency III-V Multijunction Solar Cells

We review the field of thin-film silicon solar cells with an active layer thickness of a few micrometers. These technologies can potentially lead to low cost through lower material costs than conventional modules, but do not suffer from some critical drawbacks of other thin-film technologies, such as limited supply of basic materials or toxicity of the components. Amorphous Si technology is the oldest and best established thin-film silicon technology. Amorphous silicon is deposited at low temperature
with plasma-enhanced chemical vapor deposition (PECVD). In spite of the fundamental limitation of this material due to its disorder and metastability, the technology is now gaining industrial momentum thanks to the entry of equipment manufacturers with experience with large-area PECVD. Microcrystalline Si (also called nanocrystalline Si) is a material with crystallites in the nanometer range in an amorphous matrix, and which contains less defects than amorphous silicon. Its lower bandgap makes it particularly appropriate as active material for the bottom cell in tandem and triple junction devices. The combination of an amorphous silicon top cell and a microcrystalline bottom cell has yielded promising results, but much work is needed to implement it on large-area and to limit light-induced degradation. Finally thin-film polysilicon solar cells, with grain size in the micrometer range, has recently emerged as an alternative photovoltaic technology. The layers have a grain size ranging from 1&#x2009;<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>&#x03BC;</mml:mi></mml:math>m to several tens of microns, and are formed at a temperature ranging from 600 to more than <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mrow><mml:mtext>1000</mml:mtext></mml:mrow><mml:mo>&#x2218;</mml:mo></mml:msup><mml:mtext>C</mml:mtext></mml:mrow></mml:math>. Solid Phase Crystallization has yielded the best results so far but there has recently been fast progress with seed layer approaches, particularly those using the aluminum-induced crystallization technique.

Guy  Beaucarne

Silicon Thin-Film Solar Cells

A new glass texturing method (AIT&#x2014;aluminium-induced texturisation) has recently been developed by our group. In the present work, the potential of this method is explored by fabricating PLASMA poly-Si thin-film solar cells on glass superstrates that were textured with the AIT method. Using an interdigitated metallisation scheme with a full-area Al rear contact, PLASMA cells with an efficiency of up to 7&#x25; are realised. This promising result shows that the AIT glass texturing method is fully compatible with the fabrication of poly-Si thin-film solar cells on glass using solid phase crystallisation (SPC) of PECVD-deposited amorphous silicon precursor diodes. As such, there are now two distinctly different glass texturing methods&#x2014;the AIT method and CSG Solar&#x27;s glass bead method&#x2014;that are known to be capable of producing efficient SPC poly-Si thin-film solar cells on glass.

Per I. Widenborg

Polycrystalline Silicon Thin-Film Solar Cells on AIT-Textured Glass Superstrates

This review describes recent advances in the research on dye-sensitized solar cells. After a brief discussion of the general operation principles and a presentation of record efficiencies, stability data and key technology drivers, current trends will be reviewed. The focus of this review is on materials development (sensitizers, nanostructured oxide films, and electrolyte), but commercialization aspects will also be briefly addressed. The review describes the most relevant characteristics and major trends in a compact way.

F. O. Lenzmann

J. M. Kroon

Recent Advances in Dye-Sensitized Solar Cells

Thin-film photovoltaic modules based on Cu-In-Ga-Se-S (CIS) and CdTe are already being produced with high-quality and solar conversion efficiencies of around 10&#x25;, with values up to
14&#x25; expected in the near future. The integrated interconnection of single cells into large-area
 modules of <mml:math id="E1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>0.6</mml:mn><mml:mo>&#x00D7;</mml:mo><mml:mn>1.2</mml:mn></mml:mrow></mml:math><mml:math id="E2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mtext>m</mml:mtext><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:math> enables low-cost mass production, so that thin-film modules will soon be
 able to compete with conventional silicon-wafer-based modules. This contribution provides an
 overview of the basic technologies for CdTe and CIS modules, the research and development (R&#x26;D) issues,
 production technology and capacities, the module performance in long-term outdoor testing, and their use
 in installations.

Michael Powalla

Dieter Bonnet

Thin-Film Solar Cells Based on the Polycrystalline Compound Semiconductors CIS and CdTe

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Advances in OptoElectronics publishes papers on the theory, design, fabrication, and applications of devices and components that convert light into an electrical current or, conversely, an electric current into light.

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Advances in OptoElectronics publishes papers on the theory, design, fabrication, and applications of devices and components that convert light into an electrical current or, conversely, an electric current into light.

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Advances in OptoElectronics | Hindawi

Advances in OptoElectronics

This Issue is now open for submissions.
Papers are published upon acceptance, regardless of the Special Issue publication date.

Advances in OptoElectronics

Recent Advances in Solar Cells

Recent Advances in Solar Cells

Articles

Industrial Silicon Wafer Solar Cells

Recent Advances in Solar Cells

Application of CBD-Zinc Sulfide Film as an Antireflection Coating on Very Large Area Multicrystalline Silicon Solar Cell

Recent Advances in Organic Solar Cells

Rapid Thermal Annealing and Hydrogen Passivation of Polycrystalline Silicon Thin-Film Solar Cells on Low-Temperature Glass

Advances in High-Efficiency III-V Multijunction Solar Cells

Silicon Thin-Film Solar Cells

Polycrystalline Silicon Thin-Film Solar Cells on AIT-Textured Glass Superstrates

Recent Advances in Dye-Sensitized Solar Cells

Thin-Film Solar Cells Based on the Polycrystalline Compound Semiconductors CIS and CdTe