Development of a quality control process for high-quality and reproducible printable graphene conductive electrodes

太阳能电池板正面临电极危机，因为它们通常使用银电极，而银电极的库存目前正在耗尽，而且银电极是该设备中最昂贵的元件。从这个意义上说，太阳能电池板行业正在迫切寻求一种更具可持续性和低成本的替代电极材料。石墨烯电极是理想的候选者，因为石墨烯（碳的同素异形体）是一种低成本、广泛存在的元素，可以表现出高导电性。石墨烯（功函数~ -5.0 eV）具有取代目前用作光伏器件黑色电极的金属（Ag、Cu、Al、Au，功函数= 4.3-5.1 eV）的潜力，其优点是具有较高的电化学稳定性。此外，石墨烯的特殊疏水性还可以显著提高太阳能电池的稳定性，保护它们免受水/湿气的侵害。最后，石墨烯固有的一个非常重要的优势在于它作为电极的应用非常简单，使用直接和高通量的方法与工业印刷沉积技术相匹配。不幸的是，迄今为止，由于缺乏明确的生产和质量控制协议，大多数基于石墨烯的可印刷油墨表现出明显的批次差异和低电导率值。这些变化导致石墨烯电极的电导率和机械性能（粘附性和柔韧性）不可靠。因此，目前正在进行的关于高导电性（约1欧姆/平方板电阻，这是光伏所需要的）石墨烯基电极的研究相当有限，因为市场上可用的大多数石墨烯油墨都无法生产高导电性电极。因此，到目前为止，市场上还没有高导电性和可重复性的石墨烯基油墨，这一特性将使它们能够在电子产品的许多不同领域得到应用。我们的初创公司拥有大规模生产高导电性石墨烯基可印刷油墨的革命性方法的专有技术和许可证。通过这个项目，我们将努力建立一个质量控制协议，使油墨在可重复性和机械稳健性方面充分发挥可靠操作的潜力，这些特性对太阳能电池板等应用非常重要。

Solar panels are on the verge of facing an electrode crisis, given they normally use silver electrodes, which stocks are currently depleting and they are the most expensive element of the device. In that sense, the solar panel industry is urgently seeking for an alternative electrode material, with more sustainable and low-cost character. Graphene electrodes represent ideal candidates as graphene (a carbon allotrope) is a low-cost, widely Earth-abundant element that can exhibit high electrical conductivity. Graphene (Work function ~ -5.0 eV) have the potential to replace the metals (Ag, Cu, Al, Au, work functions = 4.3-5.1 eV) currently used as the black electrode of photovoltaic devices, with the advantage of exhibiting higher electrochemical stability. In addition, the specific hydrophobicity of graphene can also significantly enhance the stability of the solar cells, protecting them from water/moisture ingress. Finally, a very important advantage inherent to graphene resides in the fact its application as electrode is extremely simple, using straightforward and high-throughput methods matching industrial printing deposition techniques.Unfortunately, to date most graphene-based printable inks exhibit significant batch-to-batch variations and low conductivity values due to the absence of a well-defined production and quality control protocol. These variation led to non-reliable performance of the graphene electrodes regarding their electrical (conductivity) and mechanical (adhesion and flexibility) properties.Thus, the ongoing research on highly conductive (with ~1 Ohm/sq sheet resistance, which is required for photovoltaics) graphene-based electrodes was rather limited to date, as the most graphene inks available on the market are not capable to produce highly conductive electrodes. Thus, highly conductive and reproducible graphene-based inks are not available on the market to date, a characteristic which will enable their application in many different sectors in electronics.Our start-up company has the know how and the licence for a revolutionary method to produce, on large scales, highly conductive graphene-based printable inks. With this project we will work to establish a quality control protocol which will enable the inks reaching the full potential regarding reliable operation in terms of reproducibility and mechanical robustness, properties that are really important for applications such as solar panels.