A Photoresponsive Red-​Hair-​Inspired Polydopamine-​Based Copolymer for Hybrid Photocapacitive Sensors

Inspired by the powerful photosensitizing properties of the red hair pigments pheomelanins, a photoresponsive cysteine-​contg. variant of the adhesive biopolymer polydopamine (pDA) is developed via oxidative copolymn. of dopamine (DA) and 5-​S-​cysteinyldopamine (CDA) in variable ratios. Chem. and spectral anal. indicate the presence of benzothiazole​/benzothiazine units akin to those of pheomelanins. p(DA​/CDA) copolymers display -​impedance properties similar to those of biol. materials and a marked photoimpedance response to light stimuli. The use of the p(DA​/CDA) copolymer to implement a soln.-​processed hybrid photocapacitive​/resistive metal-​insulator-​semiconductor (MIS) device disclosed herein is the first example of technol. exploitation of photoactive, red-​hair-​inspired biomaterials as soft enhancement layer for silicon in an optoelectronic device. The bio-​inspired materials described herein may provide the active component of new hybrid photocapacitive sensors with a chem. tunable response to visible ligh