Large magnetoresistance in $\pi$-conjugated semiconductor thin film devices

TL;DR

This study investigates large magnetoresistance effects in various pi-conjugated organic semiconductor thin film devices across a range of temperatures and magnetic fields, revealing unexplained phenomena beyond current models.

Contribution

It provides a comprehensive experimental analysis of magnetoresistance in different organic semiconductors and highlights the limitations of existing theoretical explanations.

Findings

Observed up to 10% magnetoresistance at room temperature and low magnetic fields.

Magnetoresistance varies with material and device conditions.

Existing models cannot fully explain the experimental results.

Abstract

Following the recent discovery of large magnetoresistance at room temperature in polyfluorence sandwich devices, we have performed a comprehensive magnetoresistance study on a set of organic semiconductor sandwich devices made from different pi-conjugated polymers and small molecules. The measurements were performed at different temperatures, ranging from 10K to 300K, and at magnetic fields, $B < 100mT$. We observed large negative or positive magnetoresistance (up to 10% at 300K and 10mT) depending on material and device operating conditions. We compare the results obtained in devices made from different materials with the goal of providing a comprehensive picture of the experimental data. We discuss our results in the framework of known magnetoresistance mechanisms and find that none of the existing models can explain our results.