Bidirectional optoelectronic switching in protein by photoinduced phase transition.
basic_science · Level V
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- Record sourced from PubMed, PMID 42758814.
- Also identified by DOI 10.1126/sciadv.aee6038.
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Abstract
Protein polymers conduct electricity due to the delocalization of π electrons along the conjugated main chains, but their photoconductivity often shows unidirectional tunability. We report a protein polymer with bidirectional optoelectronic conductivity because of reversible light intensity-dependent secondary structural transformation. The protein device shows a positive photocurrent under high light intensity (2.22 to 3.18 μW·μm<sup>-2</sup> and the wavelength of 405-nanometer illumination) illumination and a negative photocurrent under low light intensity (0.32 to 1.91 μW·μm<sup>-2</sup>). Under low light intensity light, the helix structures untwist into a low-conductivity β-turn because only partial hydrogen bonds are damaged by insufficient low-energy excitons and Joule heat, whereas high-intensity light drives a transition to a high-conductivity β sheet because most hydrogen bonds are destructed by high-energy excitons and sufficient Joule heat. The tunable low-conductivity state arises from an increase in β-turn content coupled with a decrease in β sheet content, while the inverse transition enables the high-conductivity state. This bidirectional conductivity enables the fibroin-based device to perform in-sensor computing for real-time perception of multiple object motions.