p-TYPE SEMICONDUCTING NICKEL OXIDE AS AN EFFICIENCY-ENHANCING ANODAL INTERFACIAL LAYER IN BULK HETEROJUNCTION SOLAR CELLS

p-Type Semiconductor Nickel Oxide As An Anodal Interfacial Layer In Organic Photovoltaics NU2007-112 Short title: p-Type Semiconductor with Nickel Oxide [for pipeline] A novel composition organic photovoltaic cell that uses a nickel oxide layer to improve stability and performance over traditional formulations. #materials #photovoltaic #semiconductor #component #energy #solar Abstract Northwestern researchers developed organic photovoltaic (OPV) cells that offer a potential alternative to conventional Si solar cells. The OPVs developed use the typical poly(3-hexylthiophene) (P3HT) and fullerene derivative [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) active layer but replace the typical electron blocking layer (EBL)/hole-transporting layer (HTL) Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with the novel composition nickel oxide. Nickel oxide (NiO), a cubic wide band-gap semiconductor, which is essentially transparent as very thin layers, is a p-type to facilitate hole conduction (HTL). This novel composition is designed to enhance OPV performance by reducing loss of open-circuit voltage that is common with other cells. NiO has a band structure well-suited for P3HT:PCBM OPVs and provides an ohmic contact to P3HT while having a sufficiently high conduction band minimum to function as an EBL. The device structure of glass/ITO/NiO/P3HT:PCBM/LiF/Al reported here proved an effective PEDOT:PSS replacement affording both exceptional fill factor (69%) and open-circuit voltage (638 mV) metrics, as well as a BHJ cell power conversion efficiency of 5.2%, versus a glass/ITO/P3HT:PCBM/LiF/Al control device (51%, 0.515mv, 2.9% respectively). Replacement of PEDOT:PSS with a p-type oxide semiconductor anode interfacial layer in an archetypical BHJ photovoltaic device results in a dramatic performance increase, while exhibiting excellent device stability. The value of such hole-transporting/electron-blocking interfacial layers is clearly demonstrated and should be applicable to other organic photovoltaics. Tags: MATERIALS: photovoltaic, SEMICONDUCTOR: component Inventors Bruce Buchholz Robert P.H. Chang Michael D Irwin Tobin J Marks Applications For use in organic photovoltaic devices Advantages o Reduced interfacial power losses in BHJ photovoltaics o Enhanced OPV device stability o Eliminate use of PEDOT:PSS in OPVs o Low cost o Lightweight with mechanical flexibility o Suitable to high-throughput, low-cost reel-to-reel coating processes Publication Irwin MD, et al. Proc Natl Acad Sci. 2008;105(8): 2783-2787. IP Status A patent application has been filed. Contact Information Allan E. Nader, Ph.D. Invention Manager (T): (847) 491-4456 (E): a-nader@northwestern.edu