Realizing high-responsive superlattice organic photodiodes by C60 and zinc phthalocyanine

Organic superlattices, consisting of alternating thin films of different organic molecules, are expected to provide new molecule assembly and unique properties that are applicable to advanced optoelectronic devices. Adopting organic superlattice as the structure of active layer may be an appropriate trade-off between planar heterojunctions and bulk heterojunction. With this structure, exciton diffusion efficiency and carrier mobility can be appropriately improved at the same time, leading to the optimization of device performance. In this paper, superlattice organic photodiodes based on heterojunction composed of C-60 and zinc phthalocyanine were fabricated and characterized. We demonstrate good optoelectronic properties of these devices with superlattice structure through experimental data. It is found that the performances of the devices are strongly dependent on the incident optical power and the number of heterojunction periods, n. We optimized n and obtained high-responsive devices. The SL-OPD with n=3 exhibits the photoresponsivity up to 5.21 (+/- 0.26) AW(-1) at the incident optical intensity of 0.068 (+/- 0.003) mWcm(-2).