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  • Phase diagram of P3HT/PCBM blends and its implication for the stability of morphology.

Phase diagram of P3HT/PCBM blends and its implication for the stability of morphology.

The journal of physical chemistry. B (2009-01-23)
Jun Zhao, Ann Swinnen, Guy Van Assche, Jean Manca, Dirk Vanderzande, Bruno Van Mele
ABSTRACT

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.

MATERIALS
Product Number
Brand
Product Description

Supelco
1,2-Dichlorobenzene, PESTANAL®, analytical standard
Sigma-Aldrich
1,2-Dichlorobenzene, suitable for HPLC, 99%
Sigma-Aldrich
1,2-Dichlorobenzene, ReagentPlus®, 99%
Sigma-Aldrich
1,2-Dichlorobenzene solution, NMR reference standard, 5% in acetone-d6 (99.9 atom % D), NMR tube size 5 mm × 8 in.