Morphology control in fullerene-based buffer layer by organic vapor phase deposition

摘要

The morphology of small molecular weight organic thin film mixtures used in organic photovoltaics (OPV) is precisely controlled through growth conditions used in organic vapor phase deposition (OVPD). We found that the crystallinity of C60 in 3, 5, 3, 5-tetra(m-pyrid-3-yl)phenyl[1,1]biphenyl (BP4mPy):C60 buffer layers undergoes changes as a function of chamber growth pressure. The chamber growth pressure is optimized at 0.28 torr, resulting in the largest C60 crystalline domains. The power conversion efficiency of organic vapor phase deposited tetraphenyldibenzoperiflanthene (DBP):C70 planar mixed heterojunction OPVs using the optimized BP4mPy:C60 buffer layer is (8.0±0.2)% compared to (6.6±0.2)% using0 amorphous buffers grown by vacuum thermal evaporation.