skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Photoinduced Charge Carrier Generation and Decay in Sequentially Deposited Polymer/Fullerene Layers: Bulk Heterojunction vs. Planar Interface

Abstract

In this work, we use the time-resolved microwave conductivity (TRMC) technique to study the dynamics of charge carrier generation in sequentially deposited conjugated polymer/fullerene layers. These layers are either fully solution-processed, using orthogonal solvents for the layers of the polymer poly(3-hexylthiophene) (P3HT) and the fullerene phenyl-C{sup 61}-butyric acid methyl ester (PCBM), or prepared by thermally evaporating a C{sup 60} layer onto P3HT films. Our work is motivated by the remarkable efficiency of organic photovoltaic (OPV) devices using a sequentially processed P3HT/PCBM active layer. Here we use an electrodeless photoconductivity probe, so we can photoexcite the sample either through the polymer or the fullerene layer. We use samples with extremely thick P3HT films (2.4 {micro}m) and show that excitation from either side of both as-cast and thermally annealed sample yields virtually identical results, consistent with mixing of the PCBM into the polymer film. We also compare solution-deposited samples to samples made by thermally evaporating C{sup 60} on P3HT, and find that we can distinguish between charge generation in bulk-P3HT and at the polymer/fullerene interface. We show that, despite their morphological differences, the carrier dynamics in the sequentially processed samples resemble those of mixed, bulk heterojunction (BHJ) systems. All of this ismore » consistent with the idea that PCBM readily mixes into the P3HT film in sequentially deposited P3HT/PCBM samples, although the total amount of fullerene mixed into the P3HT appears to be less than that typically used in an optimized BHJ. Finally, we discuss the implications for OPV device architectures prepared by sequential deposition from solution.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Energy Frontier Research Center
OSTI Identifier:
1043779
Report Number(s):
NREL/JA-5600-53772
Journal ID: ISSN 1932-7447; TRN: US201213%%457
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 116; Journal Issue: 13; Journal ID: ISSN 1932-7447
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CHARGE CARRIERS; DECAY; DEPOSITION; EFFICIENCY; ESTERS; EXCITATION; FULLERENES; HETEROJUNCTIONS; PHOTOCONDUCTIVITY; POLYMERS; SOLVENTS; time-resolved microwave conductivity; TRMC; fullerene layer; polymer film

Citation Formats

Nardes, Alexandre, Ayzner, Alexander, Hammond, Scott, Ferguson, Andrew, Schwartz, Benjamin, and Kopidakis, Nikos. Photoinduced Charge Carrier Generation and Decay in Sequentially Deposited Polymer/Fullerene Layers: Bulk Heterojunction vs. Planar Interface. United States: N. p., 2012. Web. doi:10.1021/jp212390p.
Nardes, Alexandre, Ayzner, Alexander, Hammond, Scott, Ferguson, Andrew, Schwartz, Benjamin, & Kopidakis, Nikos. Photoinduced Charge Carrier Generation and Decay in Sequentially Deposited Polymer/Fullerene Layers: Bulk Heterojunction vs. Planar Interface. United States. https://doi.org/10.1021/jp212390p
Nardes, Alexandre, Ayzner, Alexander, Hammond, Scott, Ferguson, Andrew, Schwartz, Benjamin, and Kopidakis, Nikos. Thu . "Photoinduced Charge Carrier Generation and Decay in Sequentially Deposited Polymer/Fullerene Layers: Bulk Heterojunction vs. Planar Interface". United States. https://doi.org/10.1021/jp212390p.
@article{osti_1043779,
title = {Photoinduced Charge Carrier Generation and Decay in Sequentially Deposited Polymer/Fullerene Layers: Bulk Heterojunction vs. Planar Interface},
author = {Nardes, Alexandre and Ayzner, Alexander and Hammond, Scott and Ferguson, Andrew and Schwartz, Benjamin and Kopidakis, Nikos},
abstractNote = {In this work, we use the time-resolved microwave conductivity (TRMC) technique to study the dynamics of charge carrier generation in sequentially deposited conjugated polymer/fullerene layers. These layers are either fully solution-processed, using orthogonal solvents for the layers of the polymer poly(3-hexylthiophene) (P3HT) and the fullerene phenyl-C{sup 61}-butyric acid methyl ester (PCBM), or prepared by thermally evaporating a C{sup 60} layer onto P3HT films. Our work is motivated by the remarkable efficiency of organic photovoltaic (OPV) devices using a sequentially processed P3HT/PCBM active layer. Here we use an electrodeless photoconductivity probe, so we can photoexcite the sample either through the polymer or the fullerene layer. We use samples with extremely thick P3HT films (2.4 {micro}m) and show that excitation from either side of both as-cast and thermally annealed sample yields virtually identical results, consistent with mixing of the PCBM into the polymer film. We also compare solution-deposited samples to samples made by thermally evaporating C{sup 60} on P3HT, and find that we can distinguish between charge generation in bulk-P3HT and at the polymer/fullerene interface. We show that, despite their morphological differences, the carrier dynamics in the sequentially processed samples resemble those of mixed, bulk heterojunction (BHJ) systems. All of this is consistent with the idea that PCBM readily mixes into the P3HT film in sequentially deposited P3HT/PCBM samples, although the total amount of fullerene mixed into the P3HT appears to be less than that typically used in an optimized BHJ. Finally, we discuss the implications for OPV device architectures prepared by sequential deposition from solution.},
doi = {10.1021/jp212390p},
url = {https://www.osti.gov/biblio/1043779}, journal = {Journal of Physical Chemistry. C},
issn = {1932-7447},
number = 13,
volume = 116,
place = {United States},
year = {2012},
month = {4}
}