Charge neutral, nonconjugated organic radicals have emerged as extremely useful active materials for solid-state electronic applications. This previous achievement confirmed the potential of radical-based macromolecules in organic electronic devices; however, charge transport in radical molecules has not been studied in great detail from a fundamental perspective. Here we demonstrate the charge transport in a nonconjugated organic small radical, 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (h-TEMPO). The chemical component of this radical molecule allows us to form a single crystal via physical vapor deposition (PVD). While the charge transport of this macroscopic open-shell single crystal is rather low, thermal annealing of the well-defined single crystal enables the molecule to have a rapid charge transfer reaction due to the electronic communication of open-shell sites with each other, which results in electrical conductivities greater than 0.05 S m–1. This effort demonstrates a drastically different model than the commonly accepted conjugated polymers or molecules for the creation of next-generation conductors.

Electronic wastes from transient electronics accumulate biologically harmful materials with global concern. Recycling these wastes could prevent the deposition of hazardous chemicals and toxic materials to the environment while saving scarce natural compounds and valuable resources. Here, we report a sustainable electronic device, taking advantage of carbon resources and a biodegradable cellulose composite. The device consists of an ambient-stable carbon nanotube as a semiconductor, graphene as electrodes, and a free-standing cellulose filter paper/nanocellulose composite as a dielectric layer. The dual-functional cellulose composite acting simultaneously as a robust substrate and a dielectric is demonstrated, which is compatible with solution device fabrication processes. An optimized channel dimension of 5 mm × 3 mm with the addition of ions that facilitates a charge transport realized a device with an on-current per width of 9.6 μA mm–1, an on/off ratio >102, a field-effect mobility of 2.03 cm2 V–1 s–1, and long-term stability over 30 days under ambient conditions. Successful separation of the carbonaceous components via an eco-friendly solution sorting protocol allowed the recycled device to display excellent electronic performance, with a recapture efficiency of 90%. This effort demonstrates a processable, low-cost, and sustainable electronic system that can be applied in the current realm of the semiconducting and sensing industry.

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