Organic photosensitive element and its fabrication method

Abstract

This invention relates to an organic photosensor element and its fabrication method. The organic photosensor element comprises, from bottom to top, indium tin oxide (ITO), zinc oxide (ZnO), an active layer, molybdenum trioxide (MoO3), and silver; wherein the active layer contains donor and acceptor materials. This invention fabricates the active layer using a sequential deposition method that pre-deposits the donor material and then deposits the acceptor material, and controls the thickness of the donor material layer and the overall active layer, thereby fabricating an organic photosensor element with excellent performance. In particular, it achieves an extremely low dark current density of less than 10⁻⁸ A / cm², a high responsivity of 0.45 A / W to 0.55 A / W, and a high specific detectivity (Dshot*) of 10¹² Jones to 10¹⁴ Jones. These properties are extremely important for low-light sensing.

Claims

1. An organic photosensor element, characterized by comprising, from bottom to top, indium tin oxide (ITO), zinc oxide (ZnO), an active layer, molybdenum trioxide (MoO3), and silver; the active layer contains a donor material and an acceptor material; and the mixing ratio of the donor material to the acceptor material is 1:0.73; the organic photosensor element has a dark current density of less than 10⁻⁹ A / cm² at an operating bias voltage of -2 V; wherein, The donor material comprises a D1-A1 polymer donor with the following structure: Wherein, A1 unit is a derivative of benzodithiophene; X is H, F, or Cl; R1 is a linear alkyl side chain or a branched alkyl side chain; n is an integer from 28 to 61. The acceptor material comprises an A2-D2-A2 small molecule acceptor with the following structure: Wherein, the A2 terminal group is a derivative of malononitrile; Y is H, F, Cl, or Br; D2 unit is , , , , or , where R2 is a linear alkyl side chain, a branched alkyl side chain, an oxygen-containing alkyl side chain, or a benzene-ring alkyl side chain; R3 is a linear alkyl side chain, a branched alkyl side chain, or an oxygen-containing alkyl side chain; and R4 is a sulfur or nitrogen-containing alkyl side chain.

2. The organic photosensor element as described in claim 1, wherein, The responsivity of this organic photosensor element is from 0.03 A / W to 0.55 A / W.

3. The organic photosensor element as described in claim 1, wherein, The specific detectivity Dshot* value of this organic photosensor element is between 10¹² Jones and 10¹⁴ Jones.

4. The organic photosensor element as described in claim 1, wherein, The thickness of the donor material ranges from 150 nanometers to 350 nanometers.

5. The organic photosensor element as described in claim 1, wherein, The thickness of the active layer is 300 nanometers to 600 nanometers.

6. A method for fabricating an organic photosensor element as described in any one of claims 1 to 5, characterized by comprising: Step 1: uniformly mixing zinc acetate, ethanolamine, and ethylene glycol methyl ether, and depositing the mixture onto an ITO glass substrate to obtain an ITO glass substrate coated with zinc oxide; Step 2: spin-coating a donor material dissolved in a donor solvent onto the zinc oxide-coated ITO glass substrate to complete the coating of the donor material; subsequently, spin-coating an acceptor material dissolved in an acceptor solvent onto the donor material to complete the coating of the active layer, wherein... The donor material is soluble in the solvent of the acceptor; Step 3: Molybdenum trioxide is coated on the active layer; and Step 4: Silver is coated on the molybdenum trioxide to complete the fabrication of the organic photosensor element.

7. The preparation method as described in claim 6, wherein, The concentration of the donor material is 10 mg / mL to 20 mg / mL; the concentration of the recipient material is 15 mg / mL to 25 mg / mL.

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