Probing exciton interaction with a spatially defined charge accumulation layer in the organic semiconductor Diindenoperylene

TL;DR

This study investigates how excitons interact with charge carriers in organic semiconductors, revealing a measurable reduction in photoluminescence linked to charge accumulation and estimating the non-radiative exciton-hole process cross-section.

Contribution

It provides the first combined PL and transport measurements to spatially probe exciton-charge interactions in organic thin films, specifically in Diindenoperylene.

Findings

PL intensity reduces by up to 4.5% with charge accumulation

Estimated non-radiative exciton-hole process cross-section is about 1.3E-10 cm3/s

Trapped holes are likely mediators of exciton quenching

Abstract

We present an investigation of the microscopic interplay between excitons and charge carriers by means of combined photoluminescence (PL) and charge carrier transport measurements on organic thin film transistors (OTFT). For this purpose, the prototypical organic semiconductor Diindenoperylene (DIP) was utilized as active material. The OTFT accumulation layer provides a spatially defined interaction zone for charges and photo-generated excitons leading to a PL intensity reduction of up to 4.5%. This effect correlates with the accumulated hole carrier density and provides a lower estimate of about 1.3E-10 cm3/s for the cross-section of non-radiative exciton-hole processes. It is rationalized that these processes are preferentially mediated by trapped holes.