SECTION INTRODUCTION: Thin Film Photovoltaics

The main commercial technologies in photovoltaics are based on wafers made of mono- and multicrystalline silicon, thin films made of CdTe, thin films made of CIGS and thin films made of silicon. The produced volume from all thin film plants in 2009 was around 1.6 GW with a share of around 0.6 GW for thin film silicon (for reference: the total installed power including all technologies in 2009 was around 7 GW*). Within the thin film silicon technology sector, the produced volume is split among more than 10 companies, with United Solar Ovonic, Sharp, Kaneka and Mitsubishi Heavy Industries leading the pack. The key advantages of thin film silicon are the high availability of inexpensive and environmentally friendly raw materials, and with that, a low price volatility of the essential raw materials. Further, thin film silicon production lines are based on a relatively simple production process that allows a high fab utilization and a high production yield. Finally, the produced energy per installed nominal power is inherently very high. The key challenges are the improvement in efficiency and the cost reduction for the silicon deposition tools.

In this first issue of Future Photovoltaics, Luc Feitknecht gives a comprehensive overview of the key development steps for thin film silicon technology starting in the 1970s with the first thin film silicon layers and devices. The path to highly efficient devices, including the implementation of tandem and triple junctions, is described. This includes the consequences of the Staebler-Wronski effect, which is sketched in a very descriptive way. The paper also covers the latest developments and development needs for cost-efficient deposition of the silicon layers.

*All market data taken from ACCELIOS Solar – TFPV Market Update 01/2010 (www.accelios-solar.com)

Download PDF