Panchromatic photomultiplication-type organic photodetectors with planar/bulk heterojunction structure

Broadband organic photodetectors (OPDs) can be integrated into various wearable devices and show great application potential in health monitoring and other fields. Here, we demonstrated high-performance broadband photomultiplication-type OPDs (PM-OPDs) based on MoO3 trapping electron-assisted hole tunneling injection mechanism with small-molecule lead (II) phthalocyanine (PbPc) and C-70 fullerene as the donor and acceptor, respectively. In order to control the crystal phase structure formed by PbPc molecules, we prepared PbPc:C-70 bulk heterojunction (BHJ) and PbPc/C-70 planar heterojunction (PHJ) devices. It can be seen that the PHJ device exhibits stronger near-infrared (NIR) absorption characteristics, which is more conducive to the formation of the triclinic phase structure of the PbPc molecule. We further prepared flat panchromatic PM-OPDs in the range of 300-1000 nm by using materials (PbPc and SubPc) with absorption complementary characteristic as the active layers and PHJ/BHJ hybrid heterojunction structure. The external quantum efficiency of the resulting panchromatic PM-OPDs exceeds 1000% in the whole spectral response range under -8 V reverse bias. Finally, we prepared flexible panchromatic PM-OPDs on polyethylene terephthalate substrate and successfully realized the detection of the human pulse signal. This work provides a new strategy for obtaining high-performance panchromatic PM-OPDs by designing device structures and selecting appropriate materials.