Unconventional anode interlayer universally improving solar cell efficiency
Journal
Journal of Physics D: Applied Physics
Journal Volume
51
Journal Issue
31
Pages
1-10
Date Issued
2018
Author(s)
Abstract
Organic photovoltaic cells typically employ an interlayer sandwiched between the active donor or acceptor materials and the respective electrodes. Conventionally, the employed anode interlayer (AIL) adjacent to the anode has a wide optical band gap and a significantly higher lowest unoccupied molecular orbital (LUMO) energy level, compared to the adjunct electron donor material, such as boron subphthalocyanine chloride (SubPc) studied here. In this report, we synthesized three novel AIL materials, NP-β-PCN, NPAPMLI and NPAPMLI, having narrow optical band gaps but matching the LUMO energy levels of SubPc in a planar heterojunction solar cell of ITO/SubPc/C60/BCP/Al. Upon insertion of an ultrathin (2 nm) AIL, the device power conversion efficiency is increased from 3.98% to as high as 4.92%, mainly due to the significant increase of short-circuit current density (J SC) from 5.97 to 7.11-7.65 mA cm-2. From the detailed morphological and photophysical studies, we have demonstrated that the employed unconventional materials of AIL are effective in exciton (of SubPc) blocking, thereby enhancing exciton diffusion towards the charge-separating interface of SubPc/C60 and hence J SC. Since these AIL materials all have a LUMO energy level very close to that of SubPc, the study reported here clarifies that the electron blocking is not a necessary property of an AIL material. © 2018 IOP Publishing Ltd.
Subjects
AIL; buffer layer; EBL; exciton blocking; HTL; interlayer; SubPc
SDGs
Other Subjects
Anodes; Buffer layers; Chlorine compounds; Energy gap; Excitons; Heterojunctions; Molecular orbitals; Optical band gaps; Photoelectrochemical cells; Photovoltaic cells; Heterojunction solar cells; interlayer; Lowest unoccupied molecular orbital; Organic photovoltaic cells; Photophysical studies; Power conversion efficiencies; Solar cell efficiencies; SubPc; Solar cells
Publisher
Institute of Physics Publishing
Type
journal article