Self-powered Near-infrared Organic Photodiode with Functional Interlayer*

The electromagnetic spectrum consists of ultraviolet (100-400 nm), visible (400-750 nm), and infrared (750-2500 nm) regions, among others. When the light released from any source or heating element is spectrally scattered, infrared light is outside the red edge of this band and belongs to the visible region, which contains the wavelengths that can be perceived by the human eye, The electromagnetic waves in the infrared spectrum with the shortest wavelength are known as near-infrared rays (750 – 1000 nm). Here, an organic photodiode was fabricated that can sensing light in the near-infrared wavelength band by bandgap matching the photoactive polymer for near-infrared. In addition, the organic photovoltaic was optimized through a newly synthesized functional interlayer; this layer constitutes a hole-transport layer that transfers the holes generated by the photoactive layer to the cathode easily. The material that is typically utilized for the hole transport layer is PEDOT:PSS, which has excellent heat resistance, high electrical conductivity, and transparency as advantages. However, PEDOT:PSS has drawbacks such high hydrophilicity, strong acidity, and inefficient cost. We synthesized a PPY:PSS as a hole-transport material that overcomes these drawbacks, and we optimized hole transport material by adjusting the ratio of PPY to PSS. As a result, by adding the new functional interlayer, an organic photodiode that can sense in the near-infrared range more efficiently was fabricated.