Thermal Annealing of P3HT: PCBM Organic Photovoltaic Blends

Fatma Demir, Niko Van Den Brande, Bertho Sabine, Guy Van Assche, Dirk Vanderzande, Jean Manca, Bruno Van Mele

Research output: Chapter in Book/Report/Conference proceedingConference paper


Post production annealing is an essential step for raising power conversion efficiency of bulk heterojunction solar cells [1]. Since defining appropriate annealing temperatures and times is vitally important, the isothermal crystallization of poly(3-hexyl thiophene) (P3HT) and [6,6]-phenyl C61 - butyric acid methyl ester (PCBM) blend is investigated by Rapid Heat-Cool Calorimetry (RHC), Fast Scanning Differential Chip Calorimetry (FSDCC), and AC Differential Chip Calorimetry (ACDCC).

RHC is a fast-scanning DSC technique developed by TA Instruments [2], having a 10 times smaller furnace heated by Infrared light and a sample size of about 50 to 500 µg. The RHC permits to heat at rates of up to 2000 K/min and cool at 750 K/min and 500 K/min down to 60 °C and 0 °C.

FSDCC allows temperature control of the sample and determination of its heat capacity by employing cooling and heating rates from 50 to 1 MK/s [3]. Since it is also possible to control the cooling rate, studying the kinetics of extremely fast crystallization and reorganization processes in thin films of semi-crystalline polymers on heating becomes possible.

ACDCC is used to study the step in heat capacity at the glass transition in nanometer size thin films with samples masses below 1 ng in a broad temperature range [4]. The AC-chip calorimeter allows for the frequency dependent measurement of complex heat capacity in the frequency range of 1 Hz to 1 kHz with a scan rate from 1 K/min to 5 K/min. This method is very suitable for the solar cell blends since the film thickness can be determined and applied as it is in the production line of photovoltaic devices.

The rate of crystallization during thermal annealing can be linked to the long-term stability of the blend morphology.
Original languageEnglish
Title of host publication18th Annual meeting of the Belgian Polymer Group, BPG-2011, Houffalize, Belgium
PublisherBelgian Polymer Group
Number of pages1
Publication statusPublished - 12 May 2011


  • thermal annealing
  • p3ht:pcbm solar cells
  • RHC
  • AC Chip calorimetry
  • Fast Scanning Differential Chip Calorimetry


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