Abstract:
Transition metal oxides have found application as charge transport materials
(CTMs) in perovskite solar cell devices due to their better environmental stability
and superior electronic properties compared to organic CTMs. Many researchers
have used radio frequency (RF) magnetron sputtering to deposit inorganic CTMs
on inorganic layers. However, such efforts on perovskites have been limited by
the distortion of high-energy ions of the sputtering gas energized by the RF power
and temperature. The ions may also distort the interface between transparent
conducting oxides and the charge transport layers, thereby increasing optical
scattering. Thus, the effect of ramp power during RF magnetron sputtering
deposition on the structural and optical properties of copper oxide thin films
is investigated. While the optical transmittance of the films decreases with
increased RF power, it remains the same for all ramped power films; however, it
has a similar profile as the highest RF power film. As the ramp power increases,
the X-ray diffraction shows that the films become more polycrystalline with a
monoclinic crystal structure. The energy-dispersive X-ray spectroscopy results
reveal that the atomic concentration of copper slightly increases with the RF
power, whereas oxygen concentration slightly decreases.
