Distinguishing Spin Relaxation Mechanisms in Organic Semiconductors

TL;DR

This paper introduces a theoretical framework to distinguish different spin relaxation mechanisms in organic semiconductors by analyzing their unique temperature-dependent signatures in spin relaxation and diffusion.

Contribution

The paper develops a theory that predicts distinct experimental signatures for hyperfine, spin-orbit, and intra-site relaxation mechanisms in disordered organic semiconductors.

Findings

Different mechanisms produce unique temperature-dependent signatures.

The theory provides a way to identify dominant relaxation mechanisms experimentally.

Predicted signatures can guide the design of spintronic devices.

Abstract

A theory is introduced for spin relaxation and spin diffusion of hopping carriers in a disordered system. For disorder described by a distribution of waiting times between hops (e.g. from multiple traps, site-energy disorder and/or positional disorder) the dominant spin relaxation mechanisms in organic semiconductors (hyperfine, hopping-induced spin-orbit, and intra-site spin relaxation) each produce different characteristic spin relaxation and spin diffusion dependences on temperature. The resulting unique experimental signatures predicted by the theory for each mechanism in organic semiconductors provide a prescription for determining the dominant spin relaxation mechanism.