Boron sub-2,3-naphthalocyanine chloride (SubNc) was investigated as a potential
red-sensitive organic photoconductive film (OPF). A photoconductive cell was
fabricated, and its current–voltage characteristics, both with and
without light irradiation, and external quantum efficiency (EQE) were
determined. The structure of the photoconductive cell was as follows, with
thicknesses in nm given in parentheses: glass
substrate/In–Zn–O (100)/spiro-2CBP (30)/SubNc
(50)/Alq3 (30)/Al (50) (spiro-2CBP =
2,7-bis(carbazol-9-yl)-9,9-spirobifluorene; Alq3 =
tris(8-hydroxyquinolinato)aluminum). The spiro-2CBP and Alq3 layers
were inserted between the SubNc layer and the electrodes to block dark current
injection. The three organic layers were successively deposited by evaporation
in a vacuum on the In–Zn–O-patterned substrate. SubNc film
absorbed light in the red region well, with an absorption peak at 695 nm. The
EQE of the cell reached 80% when the applied bias was 15 V. In addition, the
blocking layers effectively suppressed dark current in the OPF, which
corresponded to a current density of 20 nA/cm2 at 15 V. These results
indicate that SubNc is a promising candidate as a red-sensitive OPF.