Precise control over redox properties is essential for high-performance organic electronic devices such as organic batteries, electrochromic devices, and information storage devices. In this context, multi-redox active carbons and hydrocarbons, represented as Cx Hy molecules (x≥1, y≥0), are highly sought after, because they can switch between multiple redox states. Herein, we outline the redox properties of Cx Hy molecules as solutes and adsorbed species. Furthermore, the limitations of evaluating their redox properties and the possible solutions are summarized. Additionally, the theoretical capacity (mAh/g) and gravimetric energy density (Wh/kg) of secondary batteries were estimated based on the redox properties of 185 Cx Hy molecules, which have primarily been reported in the last decade. Among them, seven Cx Hy molecules were found to have the potential to surpass the energy density of LiNi0.6 Mn0.2 Co0.2 O2 /graphite batteries. The use of Cx Hy molecules in multielectrochromic devices and multi-bit memory is also explained. We believe that this review will encourage further utilization of Cx Hy molecules thereby promoting its applications in organic electronic devices.
Keywords: fullerenes; hydrocarbons; multi-redox active molecules; multistep electron transfer; nanographenes.
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