title: Stable inverted small molecular organic solar cells using a p-doped optical spacer.
abstract: We report inverted small molecular organic solar cells using a doped window layer as an optical spacer. The optical spacer was used to shift the optical field distribution inside the active layers, generating more charge carriers from sunlight. In this report, N,N,N',N'-tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD) was doped with 2,2-(perfluoronaphthalene-2,6-diylidene)dimalononitrile (F6-TCNNQ), a p-type dopant material. P-doped MeO-TPD was adopted as an optical spacer because it has a large energy band gap, and its conductivity can be increased by several orders of magnitude through a doping process. As a result, a power conversion efficiency of 4.15% was achieved with the doped window layer of optimized thickness. Lastly, we present significantly improved stability of the inverted devices with the MeO-TPD layer.
authors.affiliation: Graduate School of Energy, Environment, Water, and Sustainability (EEWS), Graphene Research Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea. jungyong.lee@kaist.ac.kr.
authors.forename: Sang-Hoon
authors.initials: SH
authors.lastname: Lee
authors.forename: Ji-Won
authors.initials: JW
authors.lastname: Seo
authors.forename: Jung-Yong
authors.initials: JY
authors.lastname: Lee