Room-temperature deposited fluorine-doped tantalum pentoxide for stable organic solar cells

Ermioni Polydorou, Maria Verouti, Anastasia Soultati, Konstantina-Kalliopi Armadorou, Apostolis Verykios, Petros-Panagis Filippatos, George Galanis, Konstantina Tourlouki, Nikos Kehayias, Ioannis Karatasios, Navaratnarajah Kuganathan, Alexander Chroneos, Vassilis Kilikoglou, Leonidas C. Palilis, Panagiotis Argitis, Dimitris Davazoglou, Azhar Fakharuddin, Abd Rashid bin Mohd Yusoff, Maria Vasilopoulou

Research output: Contribution to journalArticlepeer-review


Earth-abundant transition metal oxides deposited at room temperature with low-cost methods suitable for large area manufacturing can offer advances in many fields of energy related devices. Here we report the room-temperature deposition of a fluorine-doped tantalum pentoxide using a home-made, low-cost hot-wire deposition system. This novel tantalum oxyfluoride material is super hydrophobic, ultra-transparent within the visible spectrum, and possesses adequate conductivity and suitable valence band and conduction band extrema for acting as efficient hole extraction and electron blocking layer in organic solar cells with the forward architecture. By inserting this material in the form of nanoparticles deposited on top of the commonly used as hole transport layer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, higher efficiencies compared to the reference cells without the nanoparticles were demonstrated in solar cells based on blends of polymer donors with either a fullerene (where maximum achieved efficiency was improved from 6.07% to 7.90%) or a non-fullerene acceptor (reaching values of 13.48% compared to 11.32% of the reference cell). Moreover, significant improvement in device stability was achievd in unencapsulated devices continuously exposed in a humid environment for 500 h. This work demonstrates the unambiguous potential of well-designed metal oxide materials as charge transport and blocking interlayers and protective buffers in organic solar cells and beyond.
Original languageEnglish
Article number106607
Number of pages11
JournalOrganic Electronics
Early online date30 Jul 2022
Publication statusE-pub ahead of print - 30 Jul 2022


  • Tantalum pentoxide
  • Fluorine doping
  • Organic solar cells
  • Stability


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