Hybrid Solar Cells Based on Silicon

Abstract

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. In comparison with the conventional scheme, the hybrid Si-based SC system has advantages such as; (1) Higher charging current and longer timescale, which make the hybrid system have improved performances and be able to full-charge a storage battery with larger capacity during a daytime so as to power the load for a longer time; (2) much more cost effective, which makes the cost for the hybrid PV system reduced by at least 15%(Wu et al., 2005). Thus, hybrid SCs can be a cheap alternative for conventional SCs. One type of hybrid SCs is a combination of both organic and inorganic materials which combines the unique properties of inorganic semiconductors with the film forming properties of conjugated polymers. Organic materials are inexpensive, easily processable, enabling lightweight devices and their functionality can be tailored by molecular design and chemical synthesis. On the other hand, inorganic semiconductors can be manufactured as nanoparticles and inorganic semiconductor nanoparticles offer the advantage of having high absorption coefficients, size tenability and stability. By varying the size of nanoparticles the bandgap can be tuned therefore the absorption range can be tailored (Gunes & Sariciftci, 2008). These kinds of hybrid SCs based on organic-inorganic materials are fabricated by using different concepts such as solid state dye-sensitized SCs and hybrid SCs using Bulk Heterojunction (BHJ) concept such as TiOx(Hal et al., 2003), ZnO (Beek et al., 2006), CdSe (Alivisatos, 1996; Huynh et al., 2002), Cds (Greenham et al., 1996), PbS (McDonald et al.,2005), and CuInS2. Another generation of hybrid SCs are silicon-based modules due to the direct bandgap and high efficiency of Si. This system includes SC module consisting of crystalline and amorphous silicon-based SCs. The methods for enhancing the efficiencies in these types of hybrid SCs such as applying textured structures for front and back contacts as well as implementing an intermediate reflecting layer (IRL) between the individual cells of the tandem will be discussed (Meillaud et al., 2011). This chapter brings out an overview of principle and working of hybrid SCs consisting of HJ SCs which is itself devided into two groups, first organic-inorganic