Simple near-infrared photodetector based on charge transfer complexes formed in molybdenum oxide doped N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine

We have demonstrated a simple near-infrared (NIR) photodetector (PD) based on charge transfer complex (CTC) formed in molybdenum trioxide (MoO3) doped N,N'-di(naphthalene-1-yl)-N,N'-diphenyl-benzidine (NPB), which shows a photocurrent of about 0.35 A/cm2 at 3 V under 980 nm illumination. The existence of CTC formation promotes photocurrent generation which is investigated by comparison with MoO3 doped 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) film which has no CTC absorption. It can be evolved that this kind of simple-structure photodetector has potential application in the near-infrared (NIR) detection area. It is shown in this Letter that although both MoO3 and NPB have larger energy gaps of about 3 eV and weak absorption in the NIR region, the charge transfer complexes formed by mixing the two materials show an extra absorption band and good photoelectric response in the NIR region.