Thermally Stable Solution Processed Vanadium Oxide as a Hole Extraction Layer in Organic Solar Cells

Abdullah Alsulami; Jonathan Griffin; Rania Alqurashi; Hunan Yi; Ahmed Iraqi; David Lidzey; Alastair Buckley

doi:10.3390/ma9040235

Thermally Stable Solution Processed Vanadium Oxide as a Hole Extraction Layer in Organic Solar Cells

Materials (Basel). 2016 Mar 25;9(4):235. doi: 10.3390/ma9040235.

Authors

Abdullah Alsulami¹, Jonathan Griffin², Rania Alqurashi³, Hunan Yi⁴, Ahmed Iraqi⁵, David Lidzey⁶, Alastair Buckley⁷

Affiliations

¹ Department of Physics & Astronomy, University of Sheffield, Hicks Building, Hounsfield Rd., Sheffield, South Yorkshire S3 7RH, UK. asalsulami1@sheffield.ac.uk.
² Department of Physics & Astronomy, University of Sheffield, Hicks Building, Hounsfield Rd., Sheffield, South Yorkshire S3 7RH, UK. jon.griffin@sheffield.ac.uk.
³ Department of Physics & Astronomy, University of Sheffield, Hicks Building, Hounsfield Rd., Sheffield, South Yorkshire S3 7RH, UK. ralqurashi2@sheffield.ac.uk.
⁴ Department of Chemistry, University of Sheffield, Sheffield, South Yorkshire S3 7HF, UK. h.yi@ossila.com.
⁵ Department of Chemistry, University of Sheffield, Sheffield, South Yorkshire S3 7HF, UK. a.iraqi@sheffield.ac.uk.
⁶ Department of Physics & Astronomy, University of Sheffield, Hicks Building, Hounsfield Rd., Sheffield, South Yorkshire S3 7RH, UK. d.g.lidzey@sheffield.ac.uk.
⁷ Department of Physics & Astronomy, University of Sheffield, Hicks Building, Hounsfield Rd., Sheffield, South Yorkshire S3 7RH, UK. alastair.buckley@sheffield.ac.uk.

Abstract

Low-temperature solution-processable vanadium oxide (V₂O_x) thin films have been employed as hole extraction layers (HELs) in polymer bulk heterojunction solar cells. V₂O_x films were fabricated in air by spin-coating vanadium(V) oxytriisopropoxide (s-V₂O_x) at room temperature without the need for further thermal annealing. The deposited vanadium(V) oxytriisopropoxide film undergoes hydrolysis in air, converting to V₂O_x with optical and electronic properties comparable to vacuum-deposited V₂O₅. When s-V₂O_x thin films were annealed in air at temperatures of 100 °C and 200 °C, OPV devices showed similar results with good thermal stability and better light transparency. Annealing at 300 °C and 400 °C resulted in a power conversion efficiency (PCE) of 5% with a decrement approximately 15% lower than that of unannealed films; this is due to the relative decrease in the shunt resistance (R_sh) and an increase in the series resistance (R_s) related to changes in the oxidation state of vanadium.

Keywords: organic photovoltaic; photoelectron spectroscopy; solution processing; thermal stability; vanadium oxide.