Category SOLAR CELLS – NEW ASPECTS AND SOLUTIONS

Tandem cell with microcrystalline Si

Microcrystalline silicon (pc-Si) has been studied extensively for three decades and has been used for doped layers in a-Si solar cells for over 15 years. Microcrystalline silicon is a complex material consisting of conglomerates of silicon nanocrystallites embedded into amorphous silicon. It can be more easily doped than a-Si:H; but, on the other hand, it is also more sensitive to contaminants than a-Si:H. The nucleation and growth of pc-Si:H are determinant for device quality; a certain amount of amorphous material is needed for the passivation of the nanocrystallites and for the reduction of defect related absorption. During the growth of the layer, the formation of crystallites starts with a nucleation phase after an amorphous incubation phase...

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Tandem cell with multicrystalline Si

In the tandem cell configuration in 1983, Hamakawa reported the structure that a-Si: H/pc – Si heterojunction cell has been investigated as a bottom cell (Hamakawa et al. 1982). Its advantage is that it does not require high temperature processing for junction formation, and the top a-Si:H cell can be fabricated continuously. A heterojunction cell that is reported in 1994 by Matsuyama consisting of a-Si:H as p-type and pc-Si as n-type, with a 10 pm thick pc-Si film fabricated by solid phase crystallization yielded an efficiency of 8.5%. By using a p-pc-Si: C/n-pc-Si/n-pc-Si heterojunction bottom solar cell a conversion efficiency of 20.3% and good stability can be gained. At least in this type of devices the highest efficiency reported up to now is 20.4% (Green et al., 2011).

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Tandem cell

The tandem junction cell is a high-performance silicon solar cell, which is best suited for terrestrial solar power systems. The most distinctive design feature of this device is the use of only back contacts to eliminate the metal shadowing effects because of lower conversion efficiency and steady-state bias requirement. Here we discuss tandem devices consisting of the a-si:H with other forms of silicon:

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Amorphous ( protocrystalline) and microcrystalline silicon solar cells

The use of thin-film silicon for SCs is one of the most promising approaches to realize both high performance and low cost due to its low material cost, ease of manufacturing and high efficiency. Microcrystalline silicon (pc) SCs as a family of thin film SCs formed by plasma CVD at low temperature are assumed to have a shorter carrier lifetime than single-crystal cells, and it is common to employ a p-i-n structure including an internal electric field in the same way as an amorphous SC. These cells can be divided into p-i – n and n-i-p types according to the film deposition order, although the window layer of the SC is the p-type layer in both cases...

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Crystalline silicon thin film solar cells

Silicon is the leading material used in microelectronic technology and shows novel photoelectrochemical properties in electrolyte solutions ( Wang et al.,2010). Now and before Si-based cells especially crystalline Si has shown higher efficiencies. The last efficieny reported by UNSW PERL is 25% which exceeds other types of Si-based SCs (Green et al., 2011, Zhao et al., 1998).

Crystalline silicon (c-Si) is an extremely well suited material for terrestrial photovoltaics (PV). It is non-toxic and abundant (25% of the Earth’s crust), has excellent electronic, chemical and mechanical properties, forms a simple monoelemental semiconductor that has an almost ideal bandgap (1.1 eV) for terrestrial PV, and gives long-term stable SCs and modules...

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Material characterization of hybrid solar cells

Relating to the configuration of hybrid SCs like HJ SCs or dye-sensitized SCs, various materials have been suggested by research groups. The BHJ devices were characterized by an interpenetrating network of donor and acceptor materials, providing a large interface area where photo-induced excitons could efficiently dissociate into separated electrons and holes. However, the interpenetrating network cannot be easily formed in the blended mixture. In addition, the organic materials are not good in carrier transport. Thus, the power conversion efficiency is still limited by the low dissociation probability of excitons and the inefficient hopping carrier transport (Huang et al., 2009, as cited in Sirringhaus et al.,1999; Shaw et al.,2008)...

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Principle and working of hybrid solar cells

One of the methods to build hybrid SCs is Bulk Hetrojunction (BHJ) SCs, composed of two semiconductors. Excitons created upon photoexcitation are separated into free charge carriers at interfaces between two semiconductors in a composite thin film such as a conjugated polymer and fullerene mixtures. One of these materials of an HJ obviously must be an absorber. The other may be an absorber, too, or it may be a window material; i. e., a wider-gap semiconductor that contributes little or nothing to light absorption but is used to create the HJ and to support carrier transport. Window materials collect holes and electrons, which function as majority-carrier transport layers, and can separate the absorber material from deleterious recombination at contacts...

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Hybrid Solar Cells Based on Silicon

Hossein Movla1, Foozieh Sohrabi1, Arash Nikniazi1, Mohammad Soltanpour3 and Khadije Khalili2

1Faculty of Physics, University of Tabriz 2Research Institute for Applied Physics and Astronomy (RIAPA), University of Tabriz 3Faculty of Humanities and Social Sciences, University of Tabriz

Iran

1. Introduction

Human need for renewable energy resources leads to invention of renewable energy sources such as Solar Cells (SCs). Historically, the first SCs were built from inorganic materials. Although the efficiency of such conventional solar cells is high, very expensive materials and energy intensive processing techniques are required...

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