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EAI presents Cleantech Snapshots: a quick summary of some of the most interesting and innovative areas in clean technology that will drive the sustainability movement in future.


This snapshot focuses on Thin film solar. Within this page you will find


Overview

  • A Thin-film solar cell is made by depositing one or more thin layers of photovoltaic material on a substrate with very minute thickness, thus saving on material costs
  • Thin film solar cells are the new generation solar cells that contain multiple thin film layers of photo voltaic materials. The Thin Film Solar Cells (TFSC) are also known as Thin Film Photo Voltaic cell (TFPV)
  • The thicknesses of thin film layers is much less (few nanometers) compared to traditional P-N junction solar cells
  • In addition to lower material use, thin films have other advantages over crystalline silicon – better electricity output in low light and high temperatures, and flexibility that make them ideal for unique applications such as building integrated photovoltaics

Thin film solar cells

Thin film solar cells (Image source)

 

How it works

  • Thin-film solar cells are made by depositing one or more thin layers of photovoltaic material on a substrate. The thickness ranges from few nanometers to tens of micrometers
  • A semiconductor doped with phosphorus develops an excess of free electrons (usually called N type material) and a semiconductor doped with boron, gallium or indium develop a vacancy( called holes) and this doped materials known as P type materials
  • These n type and p type materials combine to form a Photo voltaic cell
  • During the absence of light, a very small amount of atoms are excited and move across the junction. This causes a small voltage drop across the junction
  • In the presence of light, more atoms are excited and flow through the junction and cause a large current at the output

Types of Thin-film Solar cells

  • Amorphous silicon (a-Si)
  • Cadmium Telluride (CdTe)
  • Copper indium gallium deselenide (CIS or CIGS)

Advantages

  • Easy to handle
  • More flexible than conventional solar cells
  • Available as thin wafer sheets
  • Cheaper than traditional panels

Applications

  • Electronic powering circuits
  • Home light applications

Drawbacks

  • Less efficiency
  • Complex structure
  • Delicate, needs to be carefully handled