title: High Efficiency Organic Solar Cells Achieved by the Simultaneous Plasmon-Optical and Plasmon-Electrical Effects from Plasmonic Asymmetric Modes of Gold Nanostars.
abstract: The plasmon-optical effects have been utilized to optically enhance active layer absorption in organic solar cells (OSCs). The exploited plasmonic resonances of metal nanomaterials are typically from the fundamental dipole/high-order modes with narrow spectral widths for regional OSC absorption improvement. The conventional broadband absorption enhancement (using plasmonic effects) needs linear-superposition of plasmonic resonances. In this work, through strategic incorporation of gold nanostars (Au NSs) in between hole transport layer (HTL) and active layer, the excited plasmonic asymmetric modes offer a new approach toward broadband enhancement. Remarkably, the improvement is explained by energy transfer of plasmonic asymmetric modes of Au NS. In more detail, after incorporation of Au NSs, the optical power in electron transport layer transfers to active layer for improving OSC absorption, which otherwise will become dissipation or leakage as the role of carrier transport layer is not for photon-absorption induced carrier generation. Moreover, Au NSs simultaneously deliver plasmon-electrical effects which shorten transport path length of the typically low-mobility holes and lengthen that of high-mobility electrons for better balanced carrier collection. Meanwhile, the resistance of HTL is reduced by Au NSs. Consequently, power conversion efficiency of 10.5% has been achieved through cooperatively plasmon-optical and plasmon-electrical effects of Au NSs.
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, P. R. China.
authors.forename: Xingang
authors.initials: X
authors.lastname: Ren
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, P. R. China.
authors.forename: Jiaqi
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
authors.forename: Shaoqing
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, P. R. China.
authors.forename: Xinchen
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, P. R. China.
authors.forename: Tingke
authors.initials: T
authors.lastname: Rao
authors.affiliation: Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
authors.forename: Lijun
authors.initials: L
authors.lastname: Huo
authors.affiliation: Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
authors.forename: Jianhui
authors.initials: J
authors.lastname: Hou
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, P. R. China. chchoy@eee.hku.hk.
authors.forename: Wallace C H
authors.initials: WC
authors.lastname: Choy
keywords: nanostar; organic solar cells; plasmon-electrical; plasmon-optical; plasmonic asymmetric modes