Transparent conductive oxides (TCOs) have been widely used as electrodes for various solar cell structures. For heterojunction silicon wafer solar cells, the front TCO layer not only serves as a top electrode (by enhancing the lateral conductance of the underlying amorphous silicon film), but also as an antireflection coating. These requirements make it difficult to simultaneously achieve excellent conductance and transparency, and thus, only high‐quality indium tin oxide (ITO) has as yet found its way into industrial heterojunction silicon wafer solar cells. In this Letter, we present a cost‐effective hybrid structure consisting of a TCO layer and a silver nano‐particle mesh. This structure enables the separate optimization of the electrical and optical requirements. The silver nanoparticle mesh provides high electrical conductance, while the TCO material is optimized as an antireflection coating. Therefore, this structure allows the use of cost‐effective (and less conductive) TCO materials, such as aluminium‐doped zinc oxide. The performance of the hybrid structure is demonstrated to achieve a similar visible transmission (∼86% in the 380–780 nm range) as an 80 nm thick ITO layer, but with 10 times better lateral conductance. The presented hybrid structure thus seems well suited for a variety of photovoltaic devices. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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The optoelectrical properties of the indium tin oxide (ITO) films are investigated at low-power and low-temperature conditions for heterojunction silicon wafer solar cell applications. ITO films deposited at 100 W in hydrogen-diluted argon ambient have the best optoelectrical quality, giving transparent and conductive (carrier mobilities in the 50-60 cm 2 /Vs range) films. X-ray diffraction analysis shows that the ITO films deposited at 100 W are primarily of amorphous (or quasiamorphous) nature, regardless of the deposition conditions. Based on several other characterisation methods, it is found that the high electron mobility achieved by the hydrogenated ITO films is mainly due to the reduction of scattering centres. A few In 2 O 3 samples are prepared at similar deposition conditions to investigate the electrical conduction mechanism of ITO films. Due to the low doping efficiency of tin atoms in amorphous ITO, the main source of the free electron charge carriers are the oxygen vacancies.