Bridging donor-acceptor energy offset using organic dopants as energy ladders to improve open-circuit voltages in bulk-heterojunction solar cells
Journal
Organic Electronics: physics, materials, applications
Journal Volume
15
Journal Issue
12
Pages
3458-3464
Date Issued
2014
Abstract
A systematic way to improve the open circuit voltage of bulk-heterojunction (BHJ) organic photovoltaics is demonstrated by incorporating energy ladder material to form a ternary blend with cascade energy structures. We propose that doping organic molecules with appropriate energetic alignment to bridge the donor-acceptor energy offset can facilitate exciton dissociation and hence improve open-circuit voltage (Voc) and power conversion efficiency. The cascade energy alignment structure is measured via ultraviolet photoemission spectroscopy. The Voc and power conversion efficiency of devices using the proposed schemes can be enhanced by 10% and 20%, respectively. The results provide a new path toward higher power conversion efficiency in BHJ systems by engineering the energy structures of the materials in the active layers. © 2014 Elsevier B.V. All rights reserved.
Subjects
Open-circuit voltage; Organic photovoltaics; Ternary cascade energy alignment
SDGs
Other Subjects
Alignment; Conversion efficiency; Doping (additives); Heterojunctions; Ladders; Open circuit voltage; Photoelectron spectroscopy; Solar cells; Timing circuits; Alignment structure; Bulk heterojunction (BHJ); Bulk heterojunction solar cells; Energy structures; Exciton dissociation; Organic photovoltaics; Power conversion efficiencies; Ultraviolet photoemission spectroscopy; Energy efficiency
Type
journal article