Near infrared photodetector (nir-pd) plays a key role in biomedical monitoring, night vision and biological imaging. Compared with traditional inorganic materials, organic semiconductors have the unique advantages of adjustable band gap, easy preparation and solution preparation. At present, organic PD with diode structure working in the near-infrared region has been reported, which has large area and flexibility. However, due to the lack of internal gain mechanism, the response rate (R) is usually lower than 1 awl-1. The external circuit (such as amplifier) is usually needed to ensure the integrity and quality of the signal, especially in the weak light detection scene. It greatly increases the complexity of practical application.

Recently, a solution treated graphene / organic near infrared phototransistor was designed and fabricated by Tao Silu, Wang Jun and others of the University of Electronic Science and technology of China. It successfully broke through the bottleneck of response rate and achieved a response rate as high as 6.1% × The response rate of 106 a W-1 improves the characteristics of graphene / organic phototransistors to a higher level, surpasses the limit of sensitivity, and opens up a new way for the development of multifunctional devices. This study is based on the theory of photomemory and pulse monitoring featured solution processed near infrared graph / organic phototransformer with detection of 2.4 × 1013 Jones published in advanced functional materials.

Highlights:

1. The ZnO electron extraction layer is creatively introduced into the graphene channel, and the organic ternary heterojunction is used as the photosensitive layer, so that the photoresponse spectrum is greatly extended to the near infrared region (760-1100 nm), the interface area between the electron donor and the electron acceptor is increased, and the problems of limited photoresponse spectrum in a single organic material and low exciton dissociation efficiency in the planar heterojunction system are overcome.

2. ZnO electron extraction layer is very important for blocking the carrier recombination process, which greatly reduces the energy loss of the device.

3. The device shows up to 6.1 × 106 a W-1 and over 2.4% × 1013 Jones (at 850 nm). It has excellent near-infrared weak light detection ability, and can produce light response even at very low power of 1.75 nwcm-2.

4. Due to the strong hole blocking effect of ZnO HOMO energy level (7.80 EV), the device can be switched to electrically erasable memory for more than 1000 s under the condition of deep hole doped graphene.

Design of near infrared graphene / organic phototransistor

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