TY - JOUR
T1 - Role of order in the mechanism of charge transport across single-stranded and double-stranded DNA monolayers in tunnel junctions
AU - Gupta, Nipun Kumar
AU - Wilkinson, Edward A
AU - Karuppannan, Senthil Kumar
AU - Bailey, Lily
AU - Vilan, Ayelet
AU - Zhang, Ziyu
AU - Qi, Dong-Chen
AU - Tadich, Anton
AU - Tuite, Eimer M
AU - Pike, Andrew R
AU - Tucker, James H R
AU - Nijhuis, Christian A
PY - 2021/12/8
Y1 - 2021/12/8
N2 - Deoxyribonucleic acid (DNA) has been hypothesized to act as a molecular wire due to the presence of an extended π-stack between base pairs, but the factors that are detrimental in the mechanism of charge transport (CT) across tunnel junctions with DNA are still unclear. Here we systematically investigate CT across dense DNA monolayers in large-area biomolecular tunnel junctions to determine when intrachain or interchain CT dominates and under which conditions the mechanism of CT becomes thermally activated. In our junctions, double-stranded DNA (dsDNA) is 30-fold more conductive than single-stranded DNA (ssDNA). The main reason for this large change in conductivity is that dsDNA forms ordered monolayers where intrachain tunneling dominates, resulting in high CT rates. By varying the temperature T and the length of the DNA fragments in the junctions, which determines the tunneling distance, we reveal a complex interplay between T, the length of DNA, and structural order on the mechanism of charge transport. Both the increase in the tunneling distance and the decrease in structural order result in a change in the mechanism of CT from coherent tunneling to incoherent tunneling (hopping). Our results highlight the importance of the interplay between structural order, tunneling distance, and temperature on the CT mechanism across DNA in molecular junctions.
AB - Deoxyribonucleic acid (DNA) has been hypothesized to act as a molecular wire due to the presence of an extended π-stack between base pairs, but the factors that are detrimental in the mechanism of charge transport (CT) across tunnel junctions with DNA are still unclear. Here we systematically investigate CT across dense DNA monolayers in large-area biomolecular tunnel junctions to determine when intrachain or interchain CT dominates and under which conditions the mechanism of CT becomes thermally activated. In our junctions, double-stranded DNA (dsDNA) is 30-fold more conductive than single-stranded DNA (ssDNA). The main reason for this large change in conductivity is that dsDNA forms ordered monolayers where intrachain tunneling dominates, resulting in high CT rates. By varying the temperature T and the length of the DNA fragments in the junctions, which determines the tunneling distance, we reveal a complex interplay between T, the length of DNA, and structural order on the mechanism of charge transport. Both the increase in the tunneling distance and the decrease in structural order result in a change in the mechanism of CT from coherent tunneling to incoherent tunneling (hopping). Our results highlight the importance of the interplay between structural order, tunneling distance, and temperature on the CT mechanism across DNA in molecular junctions.
UR - http://www.scopus.com/inward/record.url?scp=85120608599&partnerID=8YFLogxK
U2 - 10.1021/jacs.1c09549
DO - 10.1021/jacs.1c09549
M3 - Article
C2 - 34826219
SN - 0002-7863
VL - 143
SP - 20309
EP - 20319
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 48
ER -