Study On Preparation Of Near-infrared Quantum Dot Optical Devices And Chemical Warfare Agent Detection Performance

Since most chemicals and biological samples have absorption in the Near-infrared(NIR)region,the qualitative detection and the quantitative detection can be achieved by analyzing the NIR absorption spectrum of the target.NIR colloidal quantum dots(CQD)are semiconductor nanomaterials with emission wavelengths in the NIR band.The absorption and emission spectra of the quantum dots(QDs)can be adjusted by adjusting the size of the QDs,and the NIR CQD optical devices can be prepared by this properties.At present,the use of QDs materials to prepare optical devices and detecting chemical substances mainly includes the following two technical approaches: the first is to use monochromatic QDs fluorescence(emission light),or a combination of several monochromatic lights to prepare CQD light sources,qualitative and quantitative detection of substances can be realized by absorption spectral matching method.The second is to make use of the characteristics of QDs materials whose spectral characteristics would change with size to prepare array spectroscopic devices,and the spectral reconstruction of the target object be realized by the reconstruction algorithm.The disadvantage of the former is that the number of combinations of monochromatic light is limited,a single device can only detect a few chemical substances;The disadvantage of the latter is that the working waveband of the device only covers visible light and a small part of the NIR band,which needs to be further broadened.In the aspect of device preparation,there is still a lack of research on the effect of QD ink ratio on the luminescence performance and morphology of devices.In order to solve the existing disadvantages,in this subject,research work according to following three aspects has been carried out:1.Research on material selection and QD ink ratioPb S,Pb S/Cd S QDs solution and NOA are selected as filter and packaging materials.After mixing,a variety of QD inks are prepared,and a variety of NIR CQD single-point light sources and QD arrays are prepared using different ratio inks.The influence of the ink ratio on the luminous performance of the QD single-point light source and the morphology of the QD array is analyzed and studied.The results prove that when the ink ratio is less than 1:9,the single-point light source is more stable;And the QD ink ratio is 1:9,the luminous intensity of the QD single-point light source is the highest.With the increasing of ink ratio,the emission peak position of the QD single-point light source is red-shifted,and the stability of QD single-point light source is decreased.When the QD ink ratio is 1:9 and 2:8 respectively,the QD array has the best appearance,uniform light emission,neat array arrangement,high printing accuracy,and good repeatability.With the increasing of QD ink,the morphology,luminescence uniformity,and consistency of QD array are all reduced.2.Preparation and characterization of NIR QD optical devicesIn the preparation of NIR CQD single-point light sources,according to the absorption characteristics of the targets,two QD materials with emission peaks of1172±20nm and 1380±50nm are selected to prepare single-point light sources.The emission peak of the light source can be adjusted by using the red shift of the QD ink ratio change,which improves the matching degree of the absorption spectra of the target para-xylene,DMMP,methylene chloride,and dichloroethylene.The final two kinds of NIR QD single-point light sources are prepared.The emission peaks are 1169.99 nm,1379.05 nm,the half-peak widths are 132.46 nm and 155.56 nm,which prove the advantages of good luminescence performance,low power consumption and simple preparation method.For the preparation of NIR CQD array light sources,a grid deposition method for QD arrays is proposed on the basis of direct deposition.Using the ink ratio of 1:9,1:10,1:30,1:50,1:70,etc.NIR QD arrays based on glass slides,RGB dot matrix display modules,and COB LED chips are prepared.The intensity of the emission spectrum of the RGB QD array light source is high,the peak shape is good,and the luminous band range is expanded to 900-1600 nm.The number of spectral channels can be increased by increasing the number of modules,and the preparation process is relatively simple.3.Feasibility verification of target detectionIn the use of NIR CQD single-point light sources to detect targets,since the emission peak of the light source is completely matched with the absorption peaks of the target paraxylene,DMMP,dichloromethane,and dichloroethylene,so the qualitative detection of the target can be achieved.Absorbance through by calculating of the absorbance-concentration curve of 4 target substances at a concentration of 2%-100% is drawn,the standard curve is verified,and the quantitative detection of the target substance is achieved.In the use of NIR CQD arrays to detect targets,first,the empirical mode decomposition method is first used to process the signal of the array light source channel spectrum.The pre-processed array channel spectrum has a good random high-frequency noise removal effect,the randomness of the standard spectrum is reduced,and the consistency is improved.Second,a spectrum reconstruction algorithm is established based on the least square method,and noise simulation experiments are carried out on the algorithm.Finally,a NIR CQD array is used to detect ethanol gas samples,DMMP,dichloromethane,sarin,and mustard gas liquid samples,also the target absorption spectrum is reconstructed.The NIR CQD array light source with 144 spectral channels can achieve a reconstructed spectral resolution of 4.90 nm,and the minimum deviation from the characteristic peak of the standard absorption spectrum is only 0.027%,which can realize the detection of a variety of chemical agents.In this project,a systematic study on the ratio of QD inks is carried out,and the optical performance of the NIR CQD single-point light source and the shape of the array light source are effectively optimized.The matching degree of the emission spectrum of the light source and the absorption spectrum of the target is improved by adjusting the ink ratio,and the detection band of the QD spectroscopic device is broadened to900-1600 nm.The foundation for conquering the method of QD detecting chemical agents established by the preparation of NIR CQD optical devices and the application research of chemical agents detection,and it has potential application value in realizing the rapid detection of toxic harmful substances and chemical agents.