Phase diagram of P3HT/PCBM blends and its implication for the stability of morphology.
In this work, the phase diagram of poly(3-hexyl thiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) blends is measured by means of standard and modulated temperature differential scanning calorimetry. Blends were made by solvent-casting from chlorobenzene, as blends cast from toluene or 1,2-dichlorobenzene prove to retain effects of phase segregation during casting, hindering the determination of the phase diagram. The film morphology of P3HT/PCBM blends cast from chlorobenzene results from a dual crystallization behavior, in which the crystallization of each component is hindered by the other component. A single glass transition is observed for all compositions. The glass transition temperature (Tg) increases with increasing concentration of PCBM: from 12.1 degrees C for pure P3HT to 131.2 degrees C for pure PCBM. The observed Tg defines the operating window for the thermal annealing and explains the long-term instability of both the morphology and the photovoltaic performance of the P3HT/PCBM solar cells.
Zhao
Jun
J
Department of Physical Chemistry and Polymer Science, Faculty of Engineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
Swinnen
Ann
A
Van Assche
Guy
G
Manca
Jean
J
Vanderzande
Dirk
D
Van Mele
Bruno
B
D002152:Calorimetry, Differential Scanning; D002722:Chlorobenzenes / Q000737:chemistry; D003460:Crystallization; D037741:Fullerenes / Q000737:chemistry*; D008567:Membranes, Artificial; D044367:Phase Transition; D013696:Temperature; D013876:Thiophenes / Q000737:chemistry*; D014050:Toluene / Q000737:chemistry
C539575:(6,6)-phenyl C61-butyric acid methyl ester; D002722:Chlorobenzenes; D037741:Fullerenes; D008567:Membranes, Artificial; D013876:Thiophenes; C507295:poly(3-hexylthiophene); D014050:Toluene; C004726:2-dichlorobenzene; C031294:chlorobenzene