Ellmer, K.: Past achievements and future challenges in the development of optically transparent electrodes. Nature Photonics 6 (2012), p. 809-817
10.1038/NPhoton.2012.282
Abstract:
Transparent conductive electrodes (TCE) play an important and increasing role in the emerging information and energy technologies. Such materials, especially transparent conductive oxides (TCO), are already used on a large scale as transparent electrodes in many technical fields: low emissivity glass coatings, flat panel displays, thin film solar cells, or organic light emitting diodes (OLEDs). In this review the fundamental properties of TCO materials (e.g. In2O3, SnO2, ZnO, TiO2) and their current applications are summarized. Due to the increasing demand and the rising price for the raw materials (especially indium), alternatives to the dominating material indium-tin oxide (ITO) are searched for. Also, for certain purposes, for instance in solid-state lighting, lower sheet resistances are required. In the last decade carbon nanotube (CNT) and metal nanowire (MNW) networks as well as regular metal grids have been investigated as transparent electrodes. These materials, together with the recently rediscovered graphene are compared with the usual TCO materials.