The future of TCO materials : stakes and challenges

International audienceThe field of major applications of transparent conducting oxides (TCOs) continues to expand, thus generating a growing demand for new materials with lower resistivity and higher transparency over extended wavelength ranges. Moreover, p-type TCOs are opening new horizons for high-performance devices based on p-n junctions. Among the most commonly used TCO materials are zinc oxide (ZnO), indium tin oxide (ITO), tin oxide (SnO2), and indium oxide (In2O3). Still, design and synthesis of improved TCO materials leading to a marked increase in conductivity and robustness remain highly desirable while a more detailed understanding of the conductivity mechanisms is critical to further improvement. For example, there is an accelerating effort worldwide by both academia and industry to develop a transparent conductor that can meet or beat the performance of the commonly used ITO at lower costs and with more physical resilience. This article reviews new developments in TCO materials to be used in various applications spanning from photovoltaics to lighting, smart windows, or gas sensors. The financial stakes, far from being negligible in the TCOs market, and the current scientific and technological challenges to be taken up are analyzed