Polythiophene (PTh) was purchased from Sigma-Aldrich (unknown Mw), poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS, Baytron P dispersion) from H.C. Starck and fullerene (C60, 99.9% pure) from MER Corporation. All the materials were used as received. PTh and C60 were deposited by vacuum thermal evaporation from separate tungsten boats (Leybold Optics) which were heated by a Xantrex XHR 7.5–80 DC Power Supply and TDK-Lambda Genesys 8–300 DC Power Supply, respectively. The evaporation was conducted in high vacuum ∼1×10−5 Torr at a temperature of 300±15 °C. The individual rate of PTh and C60 deposition was ∼0.5–5 Å/s depending on the BHJ composition. The average overall rate was approximately ∼1.5–3 Å/s. Due to the insolubility of PTh, no accurate direct measurement of the molecular weight could be made (nor was this value indicated by the manufacturer), however a combination of different techniques in our previous work [37] suggested that the evaporated PTh is near its effective conjugation length (20–25 monomer units, Eg≈2.0 eV), which corresponds to Mw~1500–2000 g mol−1.
C60
pure
99.9%
%
DC Power Supply
7.5–80
DC Power Supply
8–300
evaporation
vacuum
∼1×10−5 Torr
Torr
evaporation
temperature
300±15 °C
°C
PTh and C60 deposition
rate
∼0.5–5 Å/s
Å/s
PTh and C60 deposition
average overall rate
∼1.5–3 Å/s
Å/s
PTh
effective conjugation length
20–25 monomer units
monomer units
PTh
Eg
≈2.0 eV
eV
PTh
Mw
~1500–2000 g mol−1
g mol−1