Ultrafast calorimetry on thin film active layers for organic photovoltaics

Niko Van Den Brande, Maxime Defour, Fatma Demir, Dirk Vanderzande, Guy Van Assche, Bruno Van Mele

Research output: Chapter in Book/Report/Conference proceedingMeeting abstract (Book)

Abstract

Bulk-heterojunction (BHJ) organic photovoltaics are based on an active layer consisting of a donor polymer and an acceptor material blend. For an optimal BHJ, this active layer has to form a phase separated co-continuous nanoscale morphology. In practise, thermal treatments (annealing) are often used to obtain the desired morphology. Using advanced fast-scanning thermal analysis techniques has made it possible to avoid the thermal effects that occur during heating or cooling (e.g. nucleation) and only study the effect of an annealing treatment. A drawback of most thermal analysis techniques however, is that they work with bulk materials. The active layers used in organic photovoltaics on the other hand, have thicknesses in the order of 100 nm.

In this study, the thermal transitions and isothermal crystallization kinetics of the P3HT:PCBM (poly[3-hexyl thiophene] : [6,6]-phenyl C61 butyric acid methyl ester) system, a benchmark BHJ system, was studied by Rapid Heating Cooling Calorimetry (RHC) [1,2] and Fast Scanning Differential Chip Calorimetry (FSDCC) [3]. This allows for thermal characterization of the blend in bulk and, for the first time, in thin layers as used in actual organic photovoltaic devices. Due to the very high scanning rates reached in FSDCC, it is now also possible to perform a similar study of pure P3HT, which is impossible using more conventional techniques due to its very fast crystallization kinetics.

[1] R.L. Danley, P.A. Caulfield, S.R. Aubuchon, American Laboratory 40 (2008) 9.
[2] F. Demir, N. Van den Brande, B. Van Mele, S. Bertho, D. Vanderzande, J. Manca, G. Van Assche, J. Therm. Anal. Calorim., 105 (2011) 845.
[3] A.A. Minakov, A.W. van Herwaarden, W. Wien, A. Wurm, C. Schick, Thermochim. Acta, 461 (2007) 96.
Original languageEnglish
Title of host publication11th European Symposium on Thermal Analysis and Calorimetry, August 17-21 2014 in Espoo, Finland
Publication statusPublished - 20 Aug 2014
Event11th European Symposium on Thermal Analysis and Calorimetry, ESTAC 11 - Espoo, Finland
Duration: 17 Aug 201421 Aug 2014

Conference

Conference11th European Symposium on Thermal Analysis and Calorimetry, ESTAC 11
CountryFinland
CityEspoo
Period17/08/1421/08/14

Keywords

  • Organic photovoltaics
  • Advanced thermal analysis
  • Chip calorimetry
  • Ultra fast scanning

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