title: An approach for an advanced anode interfacial layer with electron-blocking ability to achieve high-efficiency organic photovoltaics.
abstract: The interfacial properties of PEDOT:PSS, pristine r-GO, and r-GO with sulfonic acid (SR-GO) in organic photovoltaic are investigated to elucidate electron-blocking property of PEDOT:PSS anode interfacial layer (AIL), and to explore the possibility of r-GO as electron-blocking layers. The SR-GO results in an optimized power conversion efficiency of 7.54% for PTB7-th:PC71BM and 5.64% for P3HT:IC61BA systems. By combining analyses of capacitance-voltage and photovoltaic-parameters dependence on light intensity, it is found that recombination process at SR-GO/active film is minimized. In contrast, the devices using r-GO without sulfonic acid show trap-assisted recombination. The enhanced electron-blocking properties in PEDOT:PSS and SR-GO AILs can be attributed to surface dipoles at AIL/acceptor. Thus, for electron-blocking, the AIL/acceptor interface should be importantly considered in OPVs. Also, by simply introducing sulfonic acid unit on r-GO, excellent contact selectivity can be realized in OPVs.
authors.affiliation: Heeger Center for Advanced Materials (HCAM), School of Materials Science and Engineering, Gwangju Institute of Science and Technology , Gwangju, 500-712, Republic of Korea.
authors.forename: Jun-Seok
authors.initials: JS
authors.lastname: Yeo
authors.forename: Jin-Mun
authors.initials: JM
authors.lastname: Yun
authors.forename: Minji
authors.initials: M
authors.lastname: Kang
authors.forename: Dongyoon
authors.initials: D
authors.lastname: Khim
authors.forename: Seung-Hoon
authors.initials: SH
authors.lastname: Lee
authors.forename: Seok-Soon
authors.initials: SS
authors.lastname: Kim
authors.forename: Seok-In
authors.initials: SI
authors.lastname: Na
authors.forename: Dong-Yu
authors.initials: DY
authors.lastname: Kim
keywords: charge recombination; electron-blocking; graphene oxide; interfacial layer; organic solar cells