研究目的
Investigating the performance of solution-processed organic photodetectors for near-infrared sensing based on a novel ultranarrow-bandgap nonfullerene acceptor, CO1-4Cl.
研究成果
The study demonstrates high-performance solution-processed BHJ OPDs based on a new ultranarrow-bandgap nonfullerene acceptor, CO1-4Cl, for sensitive NIR detection. The OPDs achieved a high maximum responsivity over 0.5 A W?1 in the NIR region beyond 900 nm and a specific detectivity around 1012 Jones, close to that of a commercial Si photodiode. The devices also showed potential for practical applications, such as real-time heart-rate monitoring through photoplethysmography.
研究不足
The study acknowledges the challenge of simultaneously achieving high NIR photoresponse and low dark/noise current with narrow-bandgap materials. The performance of the photodetectors is limited by the electrical characteristics in the dark, particularly the noise level, which becomes increasingly sensitive as the bandgap of the photoactive materials becomes narrower.
1：Experimental Design and Method Selection:
The study involved the fabrication of organic photodetectors (OPDs) using a bulk-heterojunction (BHJ) system comprising a polymer donor (PTB7-Th) and a novel nonfullerene acceptor (CO1-4Cl). The devices were characterized for their photodetection performance in the NIR region.
2：Sample Selection and Data Sources:
The active layer of the OPDs was varied in thickness by adjusting the concentration of PTB7-Th:CO1-4Cl blend solutions, producing devices with two typical active layer thicknesses of ≈87 nm (thin device) and ≈300 nm (thick device).
3：List of Experimental Equipment and Materials:
The materials used include PTB7-Th, CO1-4Cl, zinc oxide as a hole-blocking layer, and molybdenum oxide with a silver top electrode. Characterization techniques included atomic force microscopy (AFM), grazing-incidence wide-angle X-ray scattering (GIWAXS), and current–voltage (J–V) measurements.
4：Experimental Procedures and Operational Workflow:
The OPDs were fabricated using an inverted architecture with solution-processed layers. The performance was evaluated under NIR illumination, and the devices were tested for responsivity, specific detectivity, and noise characteristics.
5：Data Analysis Methods:
The data were analyzed to determine the external quantum efficiency (EQE), responsivity (R), specific detectivity (D*), and noise equivalent power (NEP). The linear dynamic range (LDR) and response speed were also evaluated.
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