Overcoming the limitations of transient photovoltage measurements for studying recombination in organic solar cells
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Transient photovoltage (TPV) measurements are frequently used to study recombination processes in thin-film solar cells by probing the decay of a small optically-induced voltage perturbation to infer the charge carrier dynamics of devices at open circuit. However, the validity of this method to probe organic semiconductors has recently come into doubt due to large discrepancies in reported carrier lifetime values for the same systems, and the reporting of unrealistic reaction order values. In this work, we explore the validity of TPV to extract reliable charge carrier lifetimes in thin-film solar cells through the use of time-dependent drift diffusion simulations and measurements. We find that in low mobility materials, TPV serves primarily as a probe of charge carrier redistribution in the bulk rather than bulk recombination dynamics, and that the extracted time constant is highly mobility dependent. To address this shortcoming, we develop Transient Photo-Charge (TPQ) a new technique to measure the charge carrier density during the photo-voltage decay and apply it to study the recombination dynamics in a series of (fullerene and non-fullerene) organic solar cell systems. We show that using this technique the charge carrier recombination lifetime in the active layer can be more accurately determined.
Date Issued
2020-05-01
Date Acceptance
2020-03-02
Citation
Solar Rrl, 2020, 4 (5)
ISSN
2367-198X
Publisher
Wiley-Blackwell
Journal / Book Title
Solar Rrl
Volume
4
Issue
5
Copyright Statement
© 2020 The Authors. Published by WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Sponsor
Engineering and Physical Sciences Research Council
Subjects
Science & Technology
Technology
Energy & Fuels
Materials Science, Multidisciplinary
Materials Science
characterization tools
nonfullerene acceptors
organic solar cells
thin films
OPEN-CIRCUIT-VOLTAGE
CHARGE EXTRACTION
SEMICONDUCTOR
PHOTOCURRENT
SEPARATION
LIFETIMES
TRANSPORT
DYNAMICS
KINETICS
ACCEPTOR
Publication Status
Published
Article Number
ARTN 1900581
Date Publish Online
2020-03-04