The Negative Effect of High-Temperature Annealing on Charge-Carrier Lifetimes in Microcrystalline PCBM


  • We are grateful to Prof. J. C. Hummelen and F. B. Kooistra of the Organic Chemistry Department of the University of Groningen, The Netherlands, for providing the differential scanning calorimetry and thermogravimetric analysis data presented in Figure 4.


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Annealing microcrystalline phenyl- C61-butyric acid methyl ester (PCBM) above 100 °C results in the formation of hole traps. This is observed as an irreversible decrease in the lifetime of the transient conductivity of pulse- ionized microcrystalline PCBM powder at room temperature after annealing at different elevated temperatures (see figure). Caution is therefore advised in the routine use of pre-annealing to “improve” the performance of PCBM-based photovoltaic or field-effect transistor devices.