title: Efficient polymer solar cells enabled by low temperature processed ternary metal oxide as electron transport interlayer with large stoichiometry window.
abstract: Highly efficient organic photovoltaic cells are demonstrated by incorporating low temperature solution processed indium zinc oxide (IZO) as cathode interlayers. The IZOs are synthesized using a combustion synthesis method, which enables low temperature processes (150-250 °C). We investigated the IZO films with different electron mobilities (1.4×10(-3) to 0.23 cm2/(V·s)), hydroxide-oxide content (38% to 47%), and surface roughness (0.19-5.16 nm) by modulating the ternary metal oxide stoichiometry. The photovoltaic performance was found to be relatively insensitive to the composition ratio of In:Zn over the range of 0.8:0.2 to 0.5:0.5 despite the differences in their electrical and surface properties, achieving high power conversion efficiencies of 6.61%-7.04%. Changes in composition ratio of IZO do not lead to obvious differences in energy levels, diode parameters and morphology of the photoactive layer, as revealed by ultraviolet photoelectron spectroscopy (UPS), dark current analysis and time-of-flight secondary ion mass spectrometry (TOF-SIMS) measurements, correlating well with the large IZO stoichiometry window that enables efficient photovoltaic devices. Our results demonstrate the robustness of this ETL system and provide a convenient approach to realize a wide range of multicomponent oxides and compatible with processing on flexible plastic substrates.
authors.affiliation: †Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 3 Research Link, Singapore 117602, Singapore.
authors.forename: Wei Lin
authors.initials: WL
authors.lastname: Leong
authors.affiliation: †Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 3 Research Link, Singapore 117602, Singapore.
authors.forename: Yi
authors.initials: Y
authors.lastname: Ren
authors.affiliation: †Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 3 Research Link, Singapore 117602, Singapore.
authors.forename: Hwee Leng
authors.initials: HL
authors.lastname: Seng
authors.affiliation: †Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 3 Research Link, Singapore 117602, Singapore.
authors.forename: Zihao
authors.initials: Z
authors.lastname: Huang
authors.affiliation: †Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 3 Research Link, Singapore 117602, Singapore.
authors.forename: Sing Yang
authors.initials: SY
authors.lastname: Chiam
authors.affiliation: ‡Microelectronics Research Centre, The University of Texas at Austin, Austin, Texas 78758, United States.
authors.forename: Ananth
authors.initials: A
authors.lastname: Dodabalapur
keywords: electron transporting layer; indium zinc oxide; inverted polymer solar cells; solution process; transparent metal oxide