Role of Diffusion in Two-dimensional Bimolecular Recombination

TL;DR

This paper investigates how diffusion influences bimolecular recombination in two-dimensional organic structures, revealing that neglecting diffusion can significantly underestimate recombination rates, especially at low concentrations.

Contribution

It provides a theoretical analysis of two-dimensional Langevin recombination, identifying the critical concentration where diffusion effects become significant.

Findings

Diffusion plays a dominant role in 2D recombination at low concentrations.

Neglecting diffusion underestimates recombination rates by several times.

A critical concentration threshold for diffusion relevance is established.

Abstract

Experiments on carrier recombination in two-dimensional organic structures are often interpreted in the frame of the Langevin model with taking into account only the drift of the charge carriers in their mutual electric field. While this approach is well justified for three-dimensional systems, it is in general not valid for two-dimensional structures, where the contribution of diffusion can play a dominant role. We study the two-dimensional Langevin recombination theoretically and find the critical concentration below which diffusion cannot be neglected. For typical experimental conditions, neglecting the diffusion leads to an underestimation of the recombination rate by several times.