The analyst projects that US$1.3 billion in revenues for a-Si based solar PV this year and that this will grow to US$4.1bn in 2014, in its report Thin-Film Silicon Photovoltaic Materials.

NanoMarkets projects a relative decline against other forms of thin-film PV, but says this will happen quite slowly. Amorphous silicon currently represents about 54% of all thin-film PV shipped by value. By 2011 this number would have only slipped to 47%.

In addition, a-Si is the most likely technological route that will be taken by new entrants into the thin-film PV business, according to NanoMarkets, since manufacturing equipment and materials are readily available.

Increasing efficiencies

Amorphous silicon has been hampered in the market place by its low efficiency, but NanoMarkets believes that the development of a-Si PV cells with improved efficiency will be the key to a-Si maintaining its dominant position in the thin-film PV marketplace.

Areas where efficiency gains can be made include:

• further optimisation of the tandem-junction thin-film deposition process;
• modification of the current processes used to texturise the transparent conductive oxides (TCOs), which will improve the light-trapping efficiency and thus overall efficiency of the cell; and
• the development of materials to support the transition to nanostructured silicon, including silicon nanowires and silicon-based quantum dot absorbers, which if successful could provide a path to efficiencies above 15%.

New a-Si materials

Because of its maturity the a-Si PV market already has many players, almost all of which create PV on a rigid glass substrate. However, the NanoMarkets report believes there is an opportunity for new a-Si materials and modules firms to create a sector of the a-Si using flexible substrates.

This area has barely been touched by existing players and NanoMarkets expects materials for a-Si PV cells made on flexible substrates to take an increasing share of the a-Si PV materials market, growing from about US$178.5 million in 2011, to US$673.8m in 2016.

CdTe and CIGS on the rise

While a-Si is the dominant thin-film PV technology used today, it is already challenged by cadmium telluride (CdTe). Near the end of the forecast period other approaches in the thin-film PV landscape will also make their impact felt, especially copper indium gallium selenide (CIGS) and possibly organic PV and dye sensitive cells.