Control of Crystallinity in PbPc:C Blend Film and Application for Inverted Near-Infrared Organic Photodetector.

Inverted near-infrared (NIR) organic photodetectors (OPDs) are required to combine the OPDs with an n-channel silicon-based integrated circuit. NIR absorption in the 930-960 nm range is important because the intensity of solar irradiation is low in this wavelength regime. Here, we controlled the crystallinity of lead(II) phthalocyanine (PbPc) in a PbPc:C blend film to obtain NIR absorption. To form a triclinic phase responsible for NIR light absorption, a substrate was heated during fabrication and C was used as a templating layer, as well as an electron extraction layer, for an inverted structure. NIR absorption near 950 nm was enhanced, and the structural properties of the film changed dramatically. The OPD with enhanced NIR absorption exhibited a responsivity of 244 mA/W and an external quantum efficiency of 31.1% at a reverse bias of -3 V and 970 nm. The OPD detectivity also increased to 9.01 × 10 and 1.36 × 10 cm Hz/W under a zero bias and a reverse bias of -3 V, respectively.