The performance and morphology of vacuum co-deposited BHJs was studied through variation of four main parameters—active layer thickness, polymer–fullerene composition and post-production thermal annealing temperature and time. In order to see the effect of annealing on different PTh:C60 compositions, optimization of the annealing temperature and time had to be performed. A series of initial experiments indicated that BHJ with 80 vol% of C60 and a thickness of 70 nm lead to device characteristics comparable to the previously reported planar heterojunction devices (Jsc∼2–3 mA/cm2 and Voc∼0.40–0.45 V) [37]. This composition thus served as a good standard for optimization of the annealing parameters.
BHJ
C60
80 vol%
vol%
BHJ
thickness
70 nm
nm
planar heterojunction devices
Jsc
∼2–3 mA/cm2
mA/cm2
planar heterojunction devices
Voc
∼0.40–0.45 V
V