title: Hierarchically Structured Hole Transport Layers of Spiro-OMeTAD and Multiwalled Carbon Nanotubes for Perovskite Solar Cells.
abstract: The low electrical conductivity of spiro-OMeTAD hole transport layers impedes further enhancements of the power conversion efficiency (PCE) of perovskite solar cells. We embedded multiwalled carbon nanotubes (MWNTs) in spiro-OMeTAD (spiro-OMeTAD/MWNTs) to increase carrier mobility and conductivity. However, direct electrical contact between CH3 NH3 PbI3 and the MWNTs created pathways for undesirable back-electron transfer, owing to the large work function of MWNTs, limiting enhancements of the PCE. A hierarchical structure of pure spiro-OMeTAD and spiro-OMeTAD/MWNTs was designed to block back-electron transfer and fully exploit the enhanced charge transport of spiro-OMeTAD/MWNTs. The enhanced fill factor, short-circuit current density, open-circuit voltage, and PCE (15.1 %) were achieved by using this hierarchical hole transport layer structure (MWNT concentration=2 wt %). The perovskite solar cells were fabricated by a low-temperature solution process, further decreasing their per-Watt cost.
authors.affiliation: Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea).
authors.forename: Jiyong
authors.initials: J
authors.lastname: Lee
authors.affiliation: School of Mechanical Engineering, Sungkyunkwan University, Suwon 440-746 (Korea).
authors.forename: Mini Mol
authors.initials: MM
authors.lastname: Menamparambath
authors.affiliation: Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746 (Korea).
authors.forename: Jae-Yeol
authors.initials: JY
authors.lastname: Hwang
authors.affiliation: School of Mechanical Engineering, Sungkyunkwan University, Suwon 440-746 (Korea). sbaik@me.skku.ac.kr.|Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746 (Korea). sbaik@me.skku.ac.kr.
authors.forename: Seunghyun
authors.initials: S
authors.lastname: Baik
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D011211:Electric Power Supplies; D005449:Fluorenes / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D012993:Solar Energy; D013141:Spiro Compounds / Q000737:chemistry*; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D005449:Fluorenes; D037742:Nanotubes, Carbon; D010087:Oxides; D013141:Spiro Compounds; C059910:perovskite; C041509:fluorene; D014025:Titanium
keywords: hierarchical structure; hole transport layer; multi-walled carbon nanotubes; perovskite solar cells; spiro-ometad