Toward an Ultrahigh-Performance Near-Infrared Photoresponsive Field-Effect Transistor Using a Lead Phthalocyanine/MoS2 Organic–Inorganic Planar Heterojunction

We report a near-infrared (NIR) photoresponsive field-effect transistor that has an organic–inorganic planar heterojunction using lead phthalocyanine (PbPc)/MoS2. In the presence of NIR illumination of 0.061 μW/cm2 at 808 nm, ultrahigh photoresponsivity and external quantum efficiency were obtained, which were 1263.85 A W–1 and 194066.7%, respectively, which were much larger than those of the reference devices, when the gate voltage and drain voltage were set to 50 V using Al as the source and drain electrodes. Furthermore, from the perspective of energy level matching, the photoresponse of the gold electrode device should be superior to that of the aluminum electrode device. In addition, it would be useful to find a method of high flexibility and/or transparency that would enable it to reach its maximum potential. However, in fact, the opposite is true. Because the contact of the lead phthalocyanine thin film in the device with a gold electrode is an Ohmic contact and the contact with the aluminum electrode is a Schottky contact, different dissociated efficiencies of the photogenerated excitons are produced due to the built-in potential at the organic/electrode interface. Devices were realized via a facile solution processing method.