Plastic bioelectronics is a research field that takes advantage of the inherent properties of polymers and soft organic electronics for applications at the interface of biology and electronics. The resulting electronic materials and devices are soft, stretchable and mechanically conformable, which are important qualities for interacting with biological systems in both wearable and implantable devices. Work is currently aimed at improving these devices with a view to making the electronic-biological interface as seamless as possible.

We report the electronic structure and diverse applications of a highly luminescent ionic transition metal complex, [Ir(dF(CF 3 )ppy) 2 (dtbbpy)](PF 6 ) (where dF(CF 3 )ppy ) 2-(2,4-difluorophenyl)-5-trifluoromethylpyridine and dtbbpy ) 4,4′-di-tert-butyl-2,2′-dipyridyl). The large HOMO-LUMO gap (∆E ) 3.06 V) enabled high-energy electroluminescence from the complex. Single-layer devices were fabricated and found to emit blue-green light (500 nm). The strong reducing strength of the excited state (E* ox ) 1.21 V) enabled effective catalysis of the photoinduced reduction of H 2 O to H 2 . It was found that the relative quantum yield of hydrogen was over an order of magnitude improved from the standard photosensitizer Ru(dmphen) 3 2+ (dmphen ) 4,7-dimethyl-1,10-phenanthroline).

In vivo electrophysiological recordings of neuronal circuits are necessary for diagnostic purposes and for brain-machine interfaces. Organic electronic devices constitute a promising candidate because of their mechanical flexibility and biocompatibility. Here we demonstrate the engineering of an organic electrochemical transistor embedded in an ultrathin organic film designed to record electrophysiological signals on the surface of the brain. The device, tested in vivo on epileptiform discharges, displayed superior signal-to-noise ratio due to local amplification compared with surface electrodes. The organic transistor was able to record on the surface low-amplitude brain activities, which were poorly resolved with surface electrodes. This study introduces a new class of biocompatible, highly flexible devices for recording brain activity with superior signal-to-noise ratio that hold great promise for medical applications.