A biomaterial-silicon junction for photodetection.

Bio-integrated optoelectronics can be interfaced with biological tissues, thereby offering opportunities for clinical diagnosis and therapy. However, finding a suitable biomaterial-based semiconductor to interface with electronics is still challenging. In this study, a semiconducting layer is assembled comprising a silk protein hydrogel and melanin nanoparticles (NPs). The silk protein hydrogel provides a water-rich environment for the melanin NPs that maximizes their ionic conductivity and bio-friendliness. An efficient photodetector is produced by forming a junction between melanin NP-silk and a -type Si (-Si) semiconductor. The observed charge accumulation/transport behavior at the melanin NP-silk/-Si junction is associated with the ionic conductive state of the melanin NP-silk composite. The melanin NP-silk semiconducting layer is printed as an array on an Si substrate. The photodetector array exhibits uniform photo-response to illumination at various wavelengths, thus providing broadband photodetection. Efficient charge transfer between melanin NP-silk and Si provides fast photo-switching with rise and decay constants of 0.44 ​s and 0.19 ​s, respectively. The photodetector with a biotic interface comprising an Ag nanowire-incorporated silk layer as the top contact can operate when underneath biological tissue. The photo-responsive biomaterial-Si semiconductor junction using light as a stimulus offers a bio-friendly and versatile platform for artificial electronic skin/tissue.