NCETPEGU 2009

Emerging Technology: Organic Solar Cells

These solar cells are developed from polymers and small molecules. Compared to silicon based devices they are easy to fabricate, disposable, flexible and cheap. Prominent materials being used in the synthesis are CuPc, MEH:PPV, P3HT, Fullerene, PCBM, PEDOT:PSS and ITO along with Silver, Calcium, LiF and Aluminium acting as cathodes.

The two major technologies used are:

Polymer Technology:
- Being solution based, easy to apply
- Films are formed using simple drop and spreading method and Spin Coating.
- Amenable to large, conformal substrates
- Amenable to mixing different polymer in same solvents.
- Polymer Bulk Heterojunction Solar Cells of 6.5% efficiency have been demonstrated.

Small Molecule Technology:
- Synthesis and purity of material is easier to achieve in comparison to polymer material
- Films are formed using evaporation in 10-5 to 10-6 mbar range. These process are well understood in semiconductor industry.
- No solvent is used & hence, degradation problems related to complete solvent removal are not present.
- Small molecule Solar Cells with 5% efficiency have been demonstrated.