Flexible transparent conducting electrodes based on metal meshes for organic optoelectronic device applications: a review

Transparent conducting electrodes (TCEs) have played a pivotal role in driving the continuous development of optoelectronics technologies, which include organic optoelectronic applications. In recent years, there has been huge interest in designing innovative TCEs to replace the conventional indium tin oxide (ITO) electrodes, which suffer from complex fabrication issues and are incompatible with flexible, wearable electronic devices. In this regard, TCEs based on metal meshes are considered to be the best candidates because of their inherently high electrical conductivity, optical transparency, mechanical robustness and, more importantly, cost-competitiveness. In this review, we describe the technology developments of metal mesh-based transparent conductors and their applications in organic optoelectronic devices, including organic and perovskite solar cells, organic light emitting diodes, supercapacitors, electrochromic devices etc. Specifically, we discuss the fundamental features, optoelectronic properties, fabrication techniques and device applications of metal mesh TCEs. We also highlight the important criteria for evaluating the performance of metal mesh electrodes and propose some new research directions in this emerging field.