Scientists move closer towards mainstream use of organic PVs

One of the key barriers preventing anything but small demonstrator organic photovoltaic devices has been the electrode material.

Generally, indium tin oxide (ITO)-coated glass has been used as the transparent electrode — a material essentially borrowed from the liquid crystal display (LCD) industry.

However, it is inflexible and chemically unstable, presenting a problem for photovoltaics, which must be robust and able to cope with variable outdoor conditions.

‘Organic solar cells are very thin, typically a few hundred nanometres in thickness, and the last thing you want is any kind of chemical reaction between the organic layers and the electrode, and you don’t want atoms or ions leeching out of the electrode and into the device,’ said project lead Dr Ross Hatton of Warwick University’s chemistry department.

In addition, because the ITO-manufacturing process is sensitive to slight variations in temperature and conditions, reproducibility is a major issue.

‘A batch of ITO made in one company won’t be exactly the same as a batch of ITO made in another company — in fact, there may be batch-to-batch variations within the same company,’ Hatton said.