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Title: Monitoring the dynamics of miscible P3HT:PCBM blends: A quasi elastic neutron scattering study of organic photovoltaic active layers

Journal Article · · Polymer
 [1];  [1];  [1];  [2];  [3];  [4]
  1. Univ. of Tennessee, Knoxville, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Material Division
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical & Engineering Material Division
  4. Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division
+ Show Author Affiliations

Our work reports on the detailed molecular dynamic behavior of miscible blends of Poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and their pure counterparts by quasi-elastic neutron scattering measurements (QENS). The study provides the measure of relaxation processes on pico-to-nanosecond time scales. A single relaxation process was observed in pure P3HT and PCBM while two relaxation processes, one fast and one slow, were observed in the blends. The fast process was attributed to the dynamics of P3HT while the slow process was correlated to the dynamics of PCBM. The results show that the relaxation process is a balance between two opposing effects: increased mobility due to thermal activation of P3HT molecules and decrease mobility due to the presence of PCBM which is correlated to the percent crystallinity of P3HT and local packing density of PCBM in the amorphous phase. The threshold for the domination of the thermally activated relaxation is between 5 and 9 vol.% of PCBM loading. Two distinct spatial dependences of the relaxation processes, in which the crossover length scale depends neither on temperature nor composition, were observed for all the samples. They were attributed to the collective motions of the hexyl side chains and the rotational motions of the C-C single bonds of the side chains. Finally, these results provide an understanding of the effects of PCBM loading and temperature on the dynamics of the polymer-fullerene blends which provides a tool to optimize the efficiency of charge carrier and exciton transport within the organic photovoltaic (OPV) active layer to improve the high performance of organic solar cells.

Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
1261422
Journal Information:
Polymer, Journal Name: Polymer Journal Issue: C Vol. 61; ISSN 0032-3861
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

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  • Azuah, Richard Tumanjong; Kneller, Larry R.; Qiu, Yiming
  • Journal of Research of the National Institute of Standards and Technology, Vol. 114, Issue 6 https://doi.org/10.6028/jres.114.025
journal November 2009

Cited By (7)

Neutron Spectroscopy: An Under‐Utilised Tool for Organic Electronics Research? journal April 2019
Neutron Spectroscopy: An Under‐Utilised Tool for Organic Electronics Research? journal July 2019
Impact of side-chain length on the phase structures of P3ATs and P3AT:PCBM films as revealed by SSNMR and FTIR journal February 2018
Assessment of molecular dynamics simulations for amorphous poly(3-hexylthiophene) using neutron and X-ray scattering experiments journal January 2019
In-depth investigation of the charge extraction efficiency for thermally annealed inverted bulk-heterojunction solar cells journal January 2019
Polarization analysis on the LET cold neutron spectrometer using a 3 He spin-filter: first results journal October 2019
Morphological characterization of fullerene and fullerene-free organic photovoltaics by combined real and reciprocal space techniques journal May 2017

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Related Subjects

14 SOLAR ENERGY
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Dynamics
Neutron scattering
Organic photovoltaic