A high work function anode interfacial layer via mild temperature thermal decomposition of a C60F36 thin film on ITO

Abstract

A high work function anode interfacial layer has been developed via a mild temperature thermal decomposition of fluorinated fullerene (C₆₀F₃₆) on ITO at 120 °C. As revealed by in situ ultraviolet photoelectron spectroscopy (UPS) measurements, after the interfacial modification, the ITO electrode work function can be as high as ∼5.62 eV. It also possesses very good air stability even after the exposure to air for more than one day. The thermal annealing induced carbon–fluorine bond breaking was confirmed by in situ X-ray photoelectron spectroscopy (XPS) measurements. The residual F atoms are chemically bonded onto the ITO surface. Taking advantage of such a high work function anode interfacial layer on ITO, enhanced performance of a chloroaluminium phthalocyanine (ClAlPc)/fullerene (C₆₀) planar heterojunction based organic solar cell was observed. The performance enhancement is attributed to the higher anode WF together with the optimal nanoscale morphology, and hence better hole collection efficiency.