High-Speed Organic Photodetectors Using Heterostructure with Phthalocyanine and Perylene Derivative

Single-layered heterostructure (SLH) and multi-layered heterostructure (MLH) organic photodetectors using copper phthalocyanine (CuPc) and N , N '-bis(2,5-di- tert -butylphenyl)3,4,9,10-perylene dicarboximide (BPPC) were fabricated and characterized. The influence on the frequency response of the total thickness of the organic active layer and the incident square-wave pulse power was analyzed. For the SLH devices, a cutoff frequency of 22 MHz was obtained under an applied electric field of 0.8 MV/cm. The frequency response highly depends on the applied electric fields. However, it was not affected by the total thickness of the organic active layer. On the other hand, it was found that the frequency response speed in the MLH device was lower than that in the SLH device under a pulse light peak of 100 mW/cm 2 at the same applied reverse voltage. The cutoff frequency in the MLH device increased with the intensity of the repetition pulse light. Differences in carrier density in the quantum well between the CuPc–BPPC and the trapping levels in the hetero interface relate to the response speed.