Work

Organic semiconductor density of states controls the energy level alignment at electrode interfaces

Year: 2014

Type: article

Abstract: Minimizing charge carrier injection barriers and extraction losses at interfaces between organic semiconductors and metallic electrodes is critical for optimizing the performance of organic (opto-) electronic devices. Here, we implement a detailed electrostatic model, capable of reproducing the alignment between the electrode Fermi energy and the transport states in the organic semiconductor both qualitatively and quantitatively. Covering the full phenomenological range of interfacial energy level alignment regimes within a single, consistent framework and continuously connecting the limiting cases described by previously proposed models allows us to resolve conflicting views in the literature. Our results highlight the density of states in the organic semiconductor as a key factor. Its shape and, in particular, the energy distribution of electronic states tailing into the fundamental gap is found to determine both the minimum value of practically achievable injection barriers as well as their spatial profile, ranging from abrupt interface dipoles to extended band-bending regions. Understanding and being able to predict alignment between the electrode Fermi energy and the transport states in the organic semiconductor is important. Here, the authors report an electrostatic model, capable of reproducing the full range of interfacial energy level alignment regimes.

Source: Nature Communications

DOI: 10.1038/ncomms5174

Authors: Martin Oehzelt, Norbert Koch, Georg Heimel

Institutions: Helmholtz-Zentrum Berlin für Materialien und Energie, Humboldt-Universität zu Berlin

Language: English

Topic: Organic Electronics and Photovoltaics

Subfield: Electrical and Electronic Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $6,990

Funder: Deutsche Forschungsgemeinschaft