METHOD FOR PREPARING MID-INFRARED FOCAL PLANE DETECTOR BASED ON Sn-DOPED PbSe QUANTUM DOTS

A method for preparing a mid-infrared focal plane detector based on Sn-doped PbSe quantum dots, comprising the following steps:

• S1. depositing an Au array bottom electrode to serve as an array bottom electrode on a readout integrated circuit (ROIC) substrate by photolithography and an ion beam sputtering method;
• S2. preparing a PbS quantum dot hole transport layer on the array bottom electrode by a spin-coating method;
• S21. preparing a PbS quantum dot spin-coating solution:
• dispersing PbS quantum dots in a 25-35 mg/mL octane solution to obtain the PbS spin-coating solution;
• S22. spin-coating the PbS quantum dot spin-coating solution onto the array bottom electrode at 2,000 r/min-3,000 r/min to obtain a PbS quantum dot spin-coating layer;
• S23. treating the PbS quantum dot spin-coating layer spin-coated on the array bottom electrode with 0.1 mol of an Hydroxymethyl EDOT (EDT-methanol) solution for at least 40 seconds for ligand exchange, followed by rinsing with methanol for at least 40 seconds;
• and
• S24. repeating the step S23 to enable a dimension of the PbS quantum dot spin-coating layer to reach 100 nm-300 nm, thus completing preparation of the PbS quantum dot hole transport layer;
• S3. preparing a Sn-doped PbSe quantum dot photosensitive layer on the PbS quantum dot hole transport layer by a spin-coating method, specifically comprising:
• S31. preparing a dimethylformamide solution with dispersed Sn-doped PbSe quantum dot;
• S32. spin-coating the dimethylformamide solution with dispersed Sn-doped PbSe quantum dot onto the PbS quantum dot spin-coating layer for a period of time, followed by washing with acetonitrile;
• and
• S33. repeating the step S32 for at least two times to enable a dimension of the Sn-doped PbSe quantum dot photosensitive layer to reach 500 nm-2,000 nm, thus completing preparation of the Sn-doped PbSe quantum dot photosensitive layer;
• S4. preparing a PIN heterojunction of a ZnO electron transport layer at 200 nm-300 nm on the Sn-doped PbSe quantum dot photosensitive layer by an ion beam sputtering method;
• and
• S5. depositing an indium tin oxide (ITO) thin film at 200 nm-800 nm to serve as a top electrode on the ZnO electron transport layer by an ion beam sputtering method to obtain the mid-infrared focal plane detector;
• wherein the Sn-doped PbSe quantum dots and the PbS quantum dots are synthesized by a thermal injection method, wherein the Sn-doped PbSe quantum dots are subjected to surface modification treatment by applying a room temperature oxidation method and a liquid-phase iodination method after synthesis;
• and
• the step S31 comprises:
• S311. weighing 1.5-3 mmol of a lead acetate (II) trihydrate and 0.75-3 mmol of tin acetate (II) into a flask A, and then adding oleic acid, diphenyl ether, and trioctylphosphine into the flask A at a volume ratio of 1:1:1;
• and heating and drying the flask A under vacuum conditions at 70-90° C. for 1 hour;
• S312. dissolving 1.5-3 mmol of a selenium powder in 1 mL-2 mL of trioctylphosphine to form a trioctylphosphine selenide solution, and adding the trioctylphosphine selenide solution into the flask A in an N2 atmosphere to form a precursor solution;
• S313. weighing 1 mL of diphenyl ether into a flask B for drying under vacuum at 70-90° C. for 1 hour, and continuously raising the temperature to 240-250° C. in an N2 atmosphere;
• S314. rapidly adding all the precursor solution in the flask A into the container B to carry out a reaction for 1 minute, placing the flask B into an ice water bath for quenching and performing cooling to room temperature to obtain a Pb1−xSnxSe quantum dot reaction solution, wherein x equals 0 to 0.11;
• S315. performing centrifugation to precipitate Pb1−xSnxSe quantum dots from the Pb1−xSnxSe quantum dot reaction solution with ethanol, and re-dispersing the Pb1−xSnxSe quantum dots into a hexane solution;
• and performing centrifugation again to precipitate the Pb1−xSnxSe quantum dots from the hexane solution with an ethanol solution to obtain the Pb1−xSnxSe quantum dots, and placing the Pb1−xSnxSe quantum dots at room temperature for drying and oxidation in a low oxygen concentration atmosphere;
• S316. dispersing the Pb1−xSnxSe quantum dots obtained in the step S35 into a 15 mg/mL-25 mg/mL octane solution for liquid-phase iodization to obtain a Pb1−xSnxSe quantum dot-octane solution;
• dissolving 0.10 mol-0.2 mol of lead iodide and 0.04 mol-0.1 mol of ammonium acetate in 1 mL-2 mL of a dimethylformamide solution, and adding the resulting solution into the Pb1−xSnxSe quantum dot-octane solution at a volume ratio of 1:1;
• and performing mixing by vibration for a period of time until the Pb1−xSnxSe quantum dots are transferred from the octane solution to the dimethylformamide solution to obtain a Pb1−xSnxSe quantum dot dimethylformamide solution;
• and
• S317. performing centrifugation and precipitation on the Pb1−xSnxSe quantum dot dimethylformamide solution to obtain the Pb1−xSnxSe quantum dots, rinsing the Pb1−xSnxSe quantum dots with an octane solution to remove residual impurity ions, and then rinsing and dispersing the Pb1−xSnxSe quantum dots into a dimethylformamide solution.