Long-range light-modulated charge transport across the molecular heterostructure doped protein biopolymers

• Published in: Chemical science (Cambridge) Vol. 12; no. 25; pp. 8731 - 8739
• Main Authors: Mondal, Somen, Ghorai, Nandan, Bhunia, Soumyadip, Ghosh, Hirendra. N, Amdursky, Nadav
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 01.07.2021; The Royal Society of Chemistry
• Subjects: Biopolymers; Charge transport; Chemistry; Configurations; Electron transfer; Electrons; Heterostructures; Optoelectronic devices; Photoelectric effect; Photoelectric emission; Photosynthesis; Proteins; Separation; Transistors
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d1sc00487e

Biological electron transfer (ET) across proteins is ubiquitous, such as the notable photosynthesis example, where light-induced charge separation takes place within the reaction center, followed by sequential ET via intramolecular cofactors within the protein. Far from biology, carbon dots (C-Dots) with their unique optoelectronic properties can be considered as game-changers for next-generation advanced technologies. Here, we use C-Dots for making heterostructure (HS) configurations by conjugating them to a natural ET mediator, the hemin molecule, thus making an electron donor-acceptor system. We show by transient absorption and emission spectroscopy that the rapid intramolecular charge separation happens following light excitation, which can be ascribed to an ultrafast electron and hole transfer (HT) from the C-Dot donor to the hemin acceptor. Upon integrating the HS into a protein matrix, we show that this HT within the HS configuration is 3.3 times faster compared to the same process in solution, indicating the active role of the protein in supporting the rapid light-induced long-range intermolecular charge separation. We further use impedance, electrochemical, and transient photocurrent measurements to show that the light-induced transient charge separation results in an enhanced ET and HT efficiency across the protein biopolymer. The charge conduction across our protein biopolymers, reaching nearly 0.01 S cm −1 , along with the simplicity and low-cost of their formation promotes their use in a variety of optoelectronic devices, such as artificial photosynthesis, photo-responsive protonic-electronic transistors, and photodetectors. This work reports on a chimeric protein matrix with C-Dot-hemin heterostructures as cofactors. We show how the protein environment facilitates an ultrafast charge separation, resulting in long-range electron conduction across the protein matrix.