CVD graphene as interfacial layer to engineer the organic donor-acceptor heterojunction interface properties.
We demonstrate the use of chemical-vapor-deposited (CVD) graphene as an effective indium-tin-oxide (ITO) electrode surface modifier to engineer the organic donor-acceptor heterojunction interface properties in an inverted organic solar cell device configuration. As revealed by in situ near-edge X-ray adsorption fine structure measurement, the organic donor-acceptor heterojunction, comprising copper-hexadecafluoro-phthalocyanine (F16CuPc) and copper phthalocyanine (CuPc), undergoes an obvious orientation transition from a standing configuration (molecular π-plane nearly perpendicular to the substrate surface) on the bare ITO electrode to a less standing configuration with the molecular π-plane stacking adopting a large projection along the direction perpendicular to the electrode surface on the CVD graphene-modified ITO electrode. Such templated less-standing configuration of the organic heterojunction could significantly enhance the efficiency of charge transport along the direction perpendicular to the electrode surface in the planar heterojunction-based devices. Compared with the typical standing organic-organic heterojunction on the bare ITO electrode, our in situ ultraviolet photoelectron spectroscopy experiments reveal that the heterojunction on the CVD graphene modified ITO electrode possesses better aligned energy levels with respective electrodes, hence facilitating effective charge collection.
Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543.
Shu
S
Zhong
Jian Qiang
JQ
Zhong
Hong Ying
HY
Mao
Rui
R
Wang
Yu
Y
Wang
Dong Chen
DC
Qi
Kian Ping
KP
Loh
Andrew Thye Shen
AT
Wee
Zhi Kuan
ZK
Chen
Wei
W
Chen
D004566:Electrodes; D006108:Graphite / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry; D011789:Quantum Theory; D017971:Tin Compounds / Q000737:chemistry
D007211:Indoles; D009942:Organometallic Compounds; D017971:Tin Compounds; C549283:copper-hexadecafluoro-phthalocyanine; C015445:copper phthalocyanine; C109984:indium tin oxide; D006108:Graphite