Effect of impurities on transport through organic molecular films from first principles

TL;DR

This study uses first-principles calculations to analyze how various point defects in organic molecular films influence electron transport, revealing defect-induced features like steps and negative differential resistance in I-V characteristics.

Contribution

It provides a detailed first-principles analysis of defect effects on electron transport in organic monolayers, highlighting the impact of different defect types on transport behavior.

Findings

Single defects create steps in I-V curves.

Pairs of defects can produce negative differential resistance.

Defects introduce deep localized energy levels.

Abstract

We calculate electron transport through molecular monolayers of saturated alkanes with point defects from first principles. Single defects (incorporated Au ions, kinks, dangling bonds) produce deep localized levels in the gap between occupied and unoccupied molecular levels. Single defects produce steps on the I-V curve, whereas pairs of (unlike and like) defects give negative differential resistance peaks. The results are discussed in relation to the observed unusual transport behavior of organic monolayers and compared with transport through conjugated polythiophenes.