Exploring Electronic Characteristics of Acceptor–Donor–Acceptor‐Type Molecules by Single‐Molecule Charge Transport

Abstract

The electronic characteristics of organic optoelectronic materials determine the performance of corresponding devices. Clarifying the relationship between molecular structure and electronic characteristics at the single‐molecule level can help to achieve high performance for organic optoelectronic materials and devices, especially for organic photovoltaics. In this work, a typical acceptor–donor–acceptor (A–D–A)‐type molecule is explored by combining theoretical and experimental studies to reveal the intrinsic electronic characteristics at the single‐molecule level. Specifically, the A–D–A‐type molecule with 1,1‐dicyano methylene‐3‐indanone (INCN) acceptor units exhibits an enhanced conductance in single‐molecule junctions when compared with the control donor molecule, because the acceptor units of the A–D–A‐type molecule contribute additional transport channels. In addition, through opening the S∙∙∙O noncovalent conformational lock by protonation to expose the −S anchoring sites, the charge transport of the D central part is detected, proving that the conductive orbitals contributed by the INCN acceptor groups can penetrate the whole A–D–A molecule. These results provide important insights into the development of high‐performance organic optoelectronic materials and devices toward practical applications.

Bridging the gap from single molecule properties to organic semiconductor materials

“…In addition, it is essential to investigate molecular electronic characteristics at the single-molecule level, particularly the function of bilateral acceptor groups, because the electronic properties of acceptor–donor–acceptor type molecules control light absorption, exciton separation, and charge transportation in the photovoltaic process. Recently, Li et al 32 explored the electronic characteristics of acceptor–donor–acceptor type molecules by single-molecule charge transport. Specifically, it is discovered that the acceptor–donor–acceptor type molecules have higher conductance than the donor molecules with a shorter molecular length.…”

“…Schroeder's group 33 studied the conductance properties of a Reproduced with permission. 32 library of symmetric terphenyl derivatives with different alkyl side chains (Rn) using a STM-BJ (Fig. 5).…”

“…31 (b) Schematic illustration of single-molecule junctions for the acceptor-donor-acceptor structure using different anchor groups. Effect of the INCN acceptor on the electronic characteristics of the donor center after molecule protonation.Reproduced with permission 32.…”