Highly improved transparent conductors by combination of TCOs and metallic grids

Transparent conductive oxides (TCOs) are widely used in optoelectronic applications and are a vital part in thin film solar cells. However, these materials have some drawback, such as brittleness and a maximum transmittance for a certain sheet resistance. Alternative materials, such as metal foils, nanowires and organic conductors are discussed and ranked for their suitability in solar cells. At this moment, organic conductors have a performance inferior to inorganic conductors. Recent results obtained at TNO demonstrate that the combination of TCOs and metal grids are the most viable option for improvement of TCO performance beyond the limits of a single material. For this demonstration commercial ITO on PET was used, on which metal grid was applied by easily upscalable wet chemical deposition techniques. The sheet resistivity was increased by a factor of over 400, with less than 5% loss additional in transmittance. A sheet resistance of 0.1 Ω/sq was obtained with a transparency above 83%.