  We present a solvothermal synthetic route to produce monodispersed CuO
nanoparticles (NPs) in the range of 5-10 nm that can be used as hole selective
interfacial layer between indium tin oxide (ITO) and perovskite active layer
for p-i-n perovskite solar cells by a spin casting the dispersions at room
temperature. The bottom electrode interface modification provided by spherical
CuO-NPs at room temperature promotes the formation of high quality perovskite
photoactive layers with large crystal size and strong optical absorption.
Furthermore, it is shown that the nanoparticulate nature of the CuO hole
transporting interfacial layer can be used to improve light manipulation within
perovskite solar cell device structure. The corresponding p-i-n
CH3NH3PbI3-based solar cells show high Voc values of 1.09 V, which is
significantly higher compared to the Voc values obtained with conventional
PEDOT:PSS hole selective contact based perovskite solar cells.
