Study On The Controllable Preparation And Optoelectronic Properties Of Tin Telluride Quantum Dots

Infrared photosensitive materials are the key of infrared detector chips.The most widely studied materials have the disadvantages of harsh growth conditions,difficult to prepare in large areas,and high cost and high energy consumption owing to low temperature refrigeration needed,such as mercury cadmium telluride and type ? superlattice.Therefore,to development of new uncooled and low-cost infrared photosensitive film materials is one of the important development direction for infrared detectors in the future.Quantum dots have many advantages such as low cost,adjustable band gap,and solution processability,and have been widely used in many fields of photovoltaic cells and infrared detectors.The research on the medium wave quantum dot material mercury telluride is the most mature,but mercury telluride is highly toxic and easy to degrade.The development of new medium wave quantum dot materials is of great significance.This paper takes tin telluride(SnTe)quantum dots as the research object,and mainly conducts the following research:(1)Tin telluride quantum dots(QDs)are prepared through hot injection method.The particle size and crystallinity of the quantum dots are well controlled by precisely adjusting the reaction conditions.(2)The effects of different ligands exchange on the surface states of QDs and the photoelectric properties of thin film devices were studied,and the effects of thermal treatment on the photoelectric properties of thin film devices were further investigated.The experimental results show that 2-nitrothiophene can effectively passivate the surface of quantum dots,inhibit the oxidation of quantum dots,and realize the effective transport of photogenerated carriers between the ligand and quantum dots.The conductivity of the film which exchanged by 2-nitrothiophene exchange is 10 times higher than of without exchange,and the conductivity of the film which subjected to thermal treatment is more than 500 times higher than that before ligand exchange,the position of infrared characteristic absorption peak is red shifted apperently,the band gap is reduced also,and the improvement of photoelectric performance is qualitatively changed.The device achieves about 1 nA ultra-low dark current,and the detection rate reaches 1.8×10¹⁰Jones at 637 nm at room temperature,and a broadband photoelectic performance from visible light to 2?m wavelength.After exposed in air for 15 days in the air,it still has good photoelectric performance in the near infrared band.(3)The quantum dot colloid is combined with PCBM and P3HT without ligand exchange,where the PCBM and P3HT acted as the carriers conducting channel.The device exhibits an ultra-low dark current of 4.0×10^-11A under a40 V bias voltage.It has excellent detection performance in the near-infrared band at room temperature,and has an obvious response rate within 2 ms.The detectivity at 637 nm reaches 1.44×10¹³Jones,and the responsivity reaches5.92 A/W.The detectivity could rearch 4.20×10⁸Jones at 1310 nm.