Surrey: Nano-texturing silicon points to new photovoltaics

Research lead

Researchers at the Advanced Technology Institute (ATI) at Surrey University, United Kingdom, have developed a new technique for the laser processing of thin-film silicon for applications such as display control circuits and solar cells, which could lead to improved performance at lower costs.

The improvements are achieved using a modified laser pulse shape, resulting in the controlled transformation of amorphous silicon to its crystalline form. This allows for the fine tuning of design parameters.

Understanding how the pulse profile of the laser alters the texture of silicon films has allowed the researchers to fabricate efficient organic/inorganic hybrid solar cells, with the highest reported efficiency to date for nanocrystalline silicon and MEH-PPV polymer.

Lead investigator Damitha Adikaari comments, “The cells were initially fabricated to help us understand nanocrystalline inorganic/organic interfaces, made with laser textured nanocrystalline silicon and spin-cast MEH-PPV. However, they result in impressive photocurrents, where the bulk of the photo-generation is believed to be from the nanocrystalline silicon layer.”

The laser texturing of amorphous silicon has also been used to increase the surface area of organic photovoltaics, while keeping the device thickness to a minimum. The researchers recorded a fivefold increase in photocurrent, due to increasing the surface area.

The director of the ATI, Ravi Silva, who heads the Nano Electronics Centre where the work was carried out says, “The fundamental understanding we have gained in nano-texturing of amorphous silicon has led ATI researchers to improve charge extraction of organic/inorganic hybrid devices, which is giving rise to some exciting device physics. These nano-engineered devices promise a lot of potential for large-scale organic/inorganic photovoltaics.”