Fast scanning chip calorimetry results on 1.25 μm thin layers of PC61BM. Evolution of the PC61BM endothermic peak during heating at 30 000 K·s−1, formed by isothermal treatments at 117 °C, over 80 K below Tg, using pathway from the molten state. An initial relaxation peak around Tg is formed which then disappears as a melting peak around 300 °C starts to form. Using fast scanning chip calorimetry it was shown that PC61BM, a widespread electron acceptor for organic photovoltaics, can crystallize when isothermally treated up to 100 K below the glass transition. At such temperatures, a two-step process seems to take place, where the amorphous phase first undergoes relaxation (i.e. densification) and then crystallizes.
- Organic photovoltaics
- Electron acceptor
- Chip Calorimetry
- glass transition
- diffusionless crystallisation