am8b10321_si_001.pdf (9.6 MB)
Morphology of a Bulk Heterojunction Photovoltaic Cell with Low Donor Concentration
journal contribution
posted on 2018-08-28, 00:00 authored by Thomas Lee, Audrey Sanzogni, Ningxin Zhangzhou, Paul L. Burn, Alan E. MarkAtomistic nonequilibrium molecular
dynamics simulations have been
used to model the morphology of small-molecule bulk heterojunction
films formed by vapor deposition as used in organic photovoltaics.
Films comprising C60 and 1, 5, 10, and 50 wt % of 1,1-bis[4-bis(4-methylphenyl)aminophenyl]cyclohexane
(TAPC) were compared to films of neat C60. The simulations
suggest that if holes can hop between donor molecules separated by
as little as 1.2–1.5 nm, then a TAPC concentration of 5 wt
% is sufficient to form a percolating donor network and facilitate
charge extraction. The results provide an explanation for why low
donor content organic photovoltaics can still have high efficiencies.
In addition, the roughness, porosity, and crystallinity of the films
were found to decrease with increasing TAPC content.