# Influence of Nonuniform Exciton Density on Diffusion Length Measurements via Photoluminescence Quenching

## TL;DR

This paper shows that incorrect assumptions about exciton generation in organic solar cells can lead to up to 30% error in measuring how far excitons travel.

## Contribution

The study quantifies errors in diffusion length measurements caused by nonuniform exciton density assumptions in photoluminescence quenching.

## Key findings

- Errors in diffusion length measurements can reach up to 30% due to absorption characteristics of molecules.
- Common experimental protocols for estimating diffusion length in organic photovoltaics have significant limitations.
- Accounting for error magnitude can improve interpretation of exciton dynamics in practical setups.

## Abstract

Addressing the challenge of energy efficiency in organic
photovoltaics
(OPVs) requires investigating exciton transport mechanisms. Exciton
migration in OPVs is influenced by factors such as the morphology,
temperature, absorption properties, and excitation conditions. In
this context, the diffusion length (L
D) is a key parameter that characterizes overall transport efficiency.
Spectroscopic techniques, particularly photoluminescence quenching,
are commonly used for L
D measurements.
However, in bilayer quencher setups, these measurements can be limited
by assumptions about exciton behavior, potentially leading to inaccurate L
D estimates. In this work, we assess the magnitude
of error in L
D measurements resulting
from incorrect exciton generation assumptions. It was found that the
error largely depends on the molecules’ absorption characteristics.
An analysis of common organic compounds suggests errors of up to 30%.
The findings reveal an important limitation in commonly adopted experimental
protocols that estimate the diffusion length. Moreover, assessing
the error magnitude might aid in the interpretation of future experimental
characterizations, furthering the understanding of exciton dynamics
in practical setups.