Abstract
We enhance the efficiency of heterojunction organic solar cells by introducing a thin interfacial layer between the acceptor and donor layers. The interfacial layer energy levels are chosen to provide a gradient for charges crossing the interface, approximating a conventional p-n junction with three organic semiconductors. Devices with interfacial layers exhibit increased open circuit voltage (VOC) and increased short circuit current (JSC). The increase in VOC is due to a reduction in dark current and charge recombination. The increase in JSC is correlated with an increase in the conversion efficiency of excitons originating in the donor or acceptor layers. The interfacial layer destabilizes charge transfer states at the donor-acceptor interface, yielding reduced exciton recombination. The introduction of thin interfacial layers may prove to be an important probe of the physics of exciton separation in organic photovoltaic cells.
Highlights
The introduction of thin interfacial layers may prove to be an important probe of the physics of exciton separation in organic photovoltaic cells
It is known that organic solar cells require an interface to efficiently dissociate tightly bound excitons,7 but it is evident that charge transfer states at the donor-acceptor interface can be strongly bound
When a 10-nm-thick interfacial layer is introduced, the External quantum efficiency (EQE) associated with perylenetetracarboxylic bisbenzimidazole (PTCBI) returns to the same magnitude found for devices with no interfacial layer, while the EQE for excitons generated in m-MTDATA falls below that of the control device
Summary
Organic semiconductor photovoltaics have the potential to become a scalable, inexpensive source of solar energy generation. The technology has advanced through various device structures in recent years, including donor/acceptor heterojunctions, bulk heterojunctions, tandem structures, and the use of electrically doped transport layers. The efficiency of all devices, could benefit from improved understanding of the physics of exciton separation at the donor-acceptor interface. The efficiency of all devices, could benefit from improved understanding of the physics of exciton separation at the donor-acceptor interface. It is known that organic solar cells require an interface to efficiently dissociate tightly bound excitons, but it is evident that charge transfer states at the donor-acceptor interface can be strongly bound.. The open circuit voltage (VOC) of an organic solar cell is believed to be fundamentally limited by the energy of the bound charge transfer (CT) state, parameters like interface morphology are significant.. The VOC of organic solar cells is typically far below the fundamental limit set by the energy of the bound CT state..
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
