Advanced

Geminate Charge Recombination in Polymer/Fullerene Bulk Heterojunction Films and Implications for Solar Cell Function.

Pal, Suman Kalyan; Kesti, Tero; Maiti, Manisankar LU ; Zhang, Fengling; Inganäs, Olle; Hellström, Stefan; Andersson, Mats R; Oswald, Frederic; Langa, Fernando and Österman, Tomas LU , et al. (2010) In Journal of the American Chemical Society 132(35). p.12440-12451
Abstract
We have studied the influence of three different fullerene derivatives on the charge generation and recombination dynamics of polymer/fullerene bulk heterojunction (BHJ) solar cell blends. Charge generation in APFO3/[70]PCBM and APFO3/[60]PCBM is very similar and somewhat slower than charge generation in APFO3/[70]BTPF. This difference qualitatively matches the trend in free energy change of electron transfer estimated from the LUMO energies of the polymer and fullerene derivatives. The first order (geminate) charge recombination rate is significantly different for the three fullerene derivatives studied and increases in the order APFO3/[70]PCBM < APFO3/[60]PCBM < APFO3/[70]BTPF. The variation in electron transfer rate cannot be... (More)
We have studied the influence of three different fullerene derivatives on the charge generation and recombination dynamics of polymer/fullerene bulk heterojunction (BHJ) solar cell blends. Charge generation in APFO3/[70]PCBM and APFO3/[60]PCBM is very similar and somewhat slower than charge generation in APFO3/[70]BTPF. This difference qualitatively matches the trend in free energy change of electron transfer estimated from the LUMO energies of the polymer and fullerene derivatives. The first order (geminate) charge recombination rate is significantly different for the three fullerene derivatives studied and increases in the order APFO3/[70]PCBM < APFO3/[60]PCBM < APFO3/[70]BTPF. The variation in electron transfer rate cannot be explained from the LUMO energies of the fullerene derivatives and single-step electron transfer in the Marcus inverted region and simple considerations of expected trends for the reorganization energy and free energy change. Instead we suggest that geminate charge recombination occurs from a state where electrons and holes have separated to different distances in the various materials because of an initially high charge mobility, different for different materials. In a BHJ thin film this charge separation distance is not sufficient to overcome the electrostatic attraction between electrons and holes and geminate recombination occurs on the nanosecond to hundreds of nanoseconds time scale. In a BHJ solar cell, we suggest that the internal electric field in combination with polarization effects and the dynamic nature of polarons are key features to overcome electron-hole interactions to form free extractable charges. (Less)
Please use this url to cite or link to this publication:
author
, et al. (More)
(Less)
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of the American Chemical Society
volume
132
issue
35
pages
12440 - 12451
publisher
The American Chemical Society
external identifiers
  • wos:000281460100056
  • pmid:20704271
  • scopus:77956256131
ISSN
1520-5126
DOI
10.1021/ja104786x
language
English
LU publication?
yes
id
4fbf67f9-8a37-4eb0-b758-f7d84193c580 (old id 1665316)
date added to LUP
2010-09-09 13:51:15
date last changed
2018-05-29 09:34:09
@article{4fbf67f9-8a37-4eb0-b758-f7d84193c580,
  abstract     = {We have studied the influence of three different fullerene derivatives on the charge generation and recombination dynamics of polymer/fullerene bulk heterojunction (BHJ) solar cell blends. Charge generation in APFO3/[70]PCBM and APFO3/[60]PCBM is very similar and somewhat slower than charge generation in APFO3/[70]BTPF. This difference qualitatively matches the trend in free energy change of electron transfer estimated from the LUMO energies of the polymer and fullerene derivatives. The first order (geminate) charge recombination rate is significantly different for the three fullerene derivatives studied and increases in the order APFO3/[70]PCBM &lt; APFO3/[60]PCBM &lt; APFO3/[70]BTPF. The variation in electron transfer rate cannot be explained from the LUMO energies of the fullerene derivatives and single-step electron transfer in the Marcus inverted region and simple considerations of expected trends for the reorganization energy and free energy change. Instead we suggest that geminate charge recombination occurs from a state where electrons and holes have separated to different distances in the various materials because of an initially high charge mobility, different for different materials. In a BHJ thin film this charge separation distance is not sufficient to overcome the electrostatic attraction between electrons and holes and geminate recombination occurs on the nanosecond to hundreds of nanoseconds time scale. In a BHJ solar cell, we suggest that the internal electric field in combination with polarization effects and the dynamic nature of polarons are key features to overcome electron-hole interactions to form free extractable charges.},
  author       = {Pal, Suman Kalyan and Kesti, Tero and Maiti, Manisankar and Zhang, Fengling and Inganäs, Olle and Hellström, Stefan and Andersson, Mats R and Oswald, Frederic and Langa, Fernando and Österman, Tomas and Pascher, Torbjörn and Yartsev, Arkady and Sundström, Villy},
  issn         = {1520-5126},
  language     = {eng},
  number       = {35},
  pages        = {12440--12451},
  publisher    = {The American Chemical Society},
  series       = {Journal of the American Chemical Society},
  title        = {Geminate Charge Recombination in Polymer/Fullerene Bulk Heterojunction Films and Implications for Solar Cell Function.},
  url          = {http://dx.doi.org/10.1021/ja104786x},
  volume       = {132},
  year         = {2010},
}