CuI‐based hybrid junction in photovoltaic devices with semitransparent cathode

A hybrid inorganic/organic heterojunction formed by p‐type cuprous iodide CuI and n‐type fullerene C60 was employed in the archetypal photovoltaic devices. The thickness of the p‐CuI layer deposited on a molybdenum oxide (MoOx) anode buffer was optimized to achieve a higher efficiency, while the thickness of the n‐C60 photoabsorber layer was fixed. In an attempt to obtain semitransparent devices, a trilayer MoOx/metal/MoOx cathode with a BCP underlayer was applied (metal = Ag or Mg, BCP = bathocuproine). The maximum photovoltage of such devices on a PET/ITO substrate was equal to 0.75 V for an average transparency of about 35% over the range of 380–1000 nm. Similar devices having a non‐transparent Al cathode in conjunction with an Alq3 underlayer generate photovoltage of 0.82 V (Alq3 = tris‐8‐hydroxy­quinolinato‐aluminum), which shows the important effect of hybrid junctions in multilayer organic‐based devices.