  The rapid growth of electronic waste must be curtailed to prevent
accumulation of environmentally and biologically toxic materials, which are
essential to traditional electronics. The recent proliferation of transient
electronics has focused predominantly on biocompatibility, and studies
reporting material recapture have only demonstrated reuse of conducting
materials. Meanwhile, the ideal solution to the electronic waste
epidemic-recapture and reuse of all materials-has been largely neglected. Here
we show complete recyclability of all materials in printed, all-carbon
electronics using paper substrates, semiconducting carbon nanotubes, conducting
graphene, and insulating crystalline nanocellulose. The addition of mobile ions
to the dielectric produced significant improvements in switching speed,
subthreshold swing, and among the highest on-current for printed transistors.
These devices evinced superlative stability over 6 months, after which they are
shown to be controllably decomposed for complete recycling of materials and
re-printing of devices with similar performance to baseline devices. The
printing of all-carbon, recyclable electronics presents a new path toward green
electronics with potential to mitigate the environmental impact of electronic
waste. We anticipate all-carbon, recyclable electronics to be a watershed,
facilitating internet-of-everything applications, such as ubiquitous sensors
for continuous monitoring of diseases or environmental conditions, while
preserving carbon neutrality in the device lifecycle.
