Substrate effects on the interface electronic properties of organic photovoltaic devices with an inverted C60/CuPc junction
- 1 December 2009
- journal article
- research article
- Published by AIP Publishing in Journal of Applied Physics
- Vol. 106 (11), 114501
- https://doi.org/10.1063/1.3267163
Abstract
Deposition sequence and substrate work function in controlling the interface energy level alignment in organic photovoltaic (OPV) devices with copper phthalocyanine (CuPc) as the donor and fullerene ( C 60 ) as the acceptor were studied using ultraviolet photoelectron spectroscopy. We found that the energy offset at the highest occupied molecular orbital of donor ( HOMO D ) and the lowest unoccupied orbital of acceptor ( LUMO A ) , which limits the maximum open-circuit voltage of heterojunction OPV, can be changed from 0.64 ( C 60 on CuPc) to 0.86 eV (CuPc on C 60 ) by reversing the deposition sequence. Furthermore, by controlling the substrate work function from 2.81 to 5.07 eV, the LUMO A -HOMO D offset can be effectively tuned from 0.86 to 1.27 eV. The results suggest that electrodes in OPV devices can have significant influences on the electronic structures and energy levels of the donor/acceptor interface, and thus provide a viable means for performance enhancement.Keywords
This publication has 23 references indexed in Scilit:
- Substrate dependence of energy level alignment at the donor–acceptor interface in organic photovoltaic devicesJournal of Electron Spectroscopy and Related Phenomena, 2009
- Inverted small molecule organic photovoltaic cells on reflective substratesApplied Physics Letters, 2008
- Performance improvement of TiO2∕P3HT solar cells using CuPc as a sensitizerApplied Physics Letters, 2008
- Induced Density of States model for weakly-interacting organic semiconductor interfacesOrganic Electronics, 2007
- Offset energies at organic semiconductor heterojunctions and their influence on the open-circuit voltage of thin-film solar cellsPhysical Review B, 2007
- Electronic structures of organic/organic heterojunctions: From vacuum level alignment to Fermi level pinningJournal of Applied Physics, 2007
- High-efficiency solution processable polymer photovoltaic cells by self-organization of polymer blendsNature Materials, 2005
- Electronic structure and electrical properties of interfaces between metals and π‐conjugated molecular filmsJournal of Polymer Science Part B: Polymer Physics, 2003
- Conjugated organic molecules on metal versus polymer electrodes: Demonstration of a key energy level alignment mechanismApplied Physics Letters, 2003
- Reaction of molecular oxygen with C60: spectroscopic studiesJournal of the Chemical Society, Faraday Transactions, 1994