# Photoconductance of organic single-molecule contacts

## TL;DR

This paper investigates how external electromagnetic radiation can significantly enhance the conductance of organic single-molecule contacts, potentially transforming their electronic properties by photoassisted processes.

## Contribution

It demonstrates that photoconductance can be expressed using the transmission function without radiation and shows conductance enhancement in oligophenylene molecules due to photoassisted resonance.

## Key findings

- Radiation can induce large conductance enhancements.
- Conductance decay with length can be suppressed by radiation.
- Photoconductance can be modeled via the transmission function.

## Abstract

We study the dc conductance of organic single-molecule contacts in the presence of external electromagnetic radiation (photoconductance). In agreement with previous predictions, we find that the radiation can lead to large enhancements of the conductance of such contacts by bringing off-resonant levels into resonance through photoassisted processes. In our analysis we make use of the simplifying fact that, under certain assumptions, the photoconductance can be expressed in terms of the transmission function in the absence of the radiation. The conductance enhancement is demonstrated for oligophenylene molecules between gold electrodes, whose electronic structure is calculated based on density-functional theory. It is shown that the exponential decay of the conductance with the length of the molecule can be replaced by a length-independent value in the presence of radiation.