P3HT가 도핑된 황화납 양자점 기반의 고감도 이산화질소 가스 센서

권진범,정대웅,하윤태,최수지,백수빈 한국센서학회 2023 센서학회지 Vol.32 No.3

With the increasing concern of global warming caused by greenhouse gases owing to the recent industrial development, there is a growing need for advanced technology to control these emissions. Among the various greenhouse gases, nitrogen dioxide (NO2) is a major contributor to global warming and is mainly released from sources, such as automobile exhaust and factories. Although semiconductor-type NO2 gas sensors, such as SnO2, have been extensively studied, they often require high operating temperatures and complicated manufacturing processes, while lacking selectivity, resulting in inaccurate measurements of NO2 gas levels. To address these limitations, a novel sensor using PbS quantum dots (QDs) was developed, which operates at low temperatures and exhibits high selectivity toward NO2 gas owing to its strong oxidation reaction. Furthermore, the use of P3HT conductive polymer improved the thin film quality, reactivity, and reaction rate of the sensor.The sensor demonstrated the ability to accurately measure NO2 gas concentrations ranging from 500 to 100 ppm, with a 5.1 times higher sensitivity, 1.5 times higher response rate, and 1.15 times higher recovery rate compared with sensors withoutP3HT.

Eye safety 라이다 센서용 황화납 양자점 기반 SWIR photodetector 개발

최수지,권진범,하윤태,정대웅 한국센서학회 2023 센서학회지 Vol.32 No.5

Recently, the demand for lidar systems for autonomous driving is increasing, and research on Shortwave Infrared(SWIR)photodetectors for this purpose is being actively conducted. Most SWIR photodetectors currently being developed are basedon InGaAs, and have the disadvantages of complex processes, high prices, and limitations in research due to monopoly. In addition,current SWIR photodetectors use lasers in the 905 nm wavelength band, which can pass through the pupil and cause damageto the retina. Therefore, it is required to develop a SWIR photodetector using a wavelength band of 1400 nm or more tobe safe for human eyes, and to develop a material that can replace the proprietary InGaAs. PbS QDs are group 4-6 compoundsemiconductors whose absorption wavelength band can be adjusted from 1000 to 2700 nm, and have the advantage of beingsimple to process. Therefore, in this study, PbS QDs having an absorption wavelength peak of 1415 nm were synthesized, anda SWIR photodetector was fabricated using this. In addition, the photodetector's responsivity was improved by applying P3HTand ZnO NPs to improve electron hole mobility. As a result of the experiment, it was confirmed that the synthesized PbS QDshad excellent FWHM characteristics compared to commercial PbS QDs, and it was confirmed that the photodetector had a maximumcurrent change of about 1.6 times.

Optimization of Cd2+ partial electrolyte treatment on the absorber layer for high-efficiency Cu2ZnSnSe4 solar cells

김옥식,권진범,김세완,Binrui Xu,배진혁,손대호,김영일,김세윤,김대환,강진규,강신원 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.80 No.-

Currently, many researchers are focused on promising new energy technologies such as Cu2ZnSnS4-basedsolar cells to replace fossil fuel sources. Investigations into a variety of methods have been done toanalyze the interfacial problems and improve the cell interfacial properties via a variety of methods. Inparticular, In order to improve the electrical performance of Cu2ZnSnSe4 (CZTSe) based solar cells, the Cdpartial electrolyte (Cd PE) treatment that is an effective method in CIGS solar cells prior to applying theirCdS buffer layer to their absorber layer has been studied. In our study, we investigated the Cd PEtreatment time, the Cd PE bath temperature, and the correlation between Cd PE treatment and CdSthickness. The optimum Cd PE absorber treatment was 7 min at 70 C, with a CdS layer of 35 nm thickdeposited cells. This combination increased photo-carrier collection in the short wavelength range andreduced absorber-buffer interface recombination. The efficiency of a 35 nm buffer layer sample withoutPE treatment was 8.90%. The efficiency of another 35 nm buffer layer sample was 10.38% (Voc: 441 mV,Jsc: 38.15 mA/cm2, and FF: 61.58%) after Cd PE treatment due to the increase of Jsc, FF and Rs despite thedeficit of Voc.

MAPI 리간드 치환형 PbS 양자점 기반의 고감도 단파장 적외선 광 검출기 개발

최수지,권진범,하윤태,정대웅 한국센서학회 2024 센서학회지 Vol.33 No.2

With the development of promising future mobility and urban air mobility (UAM) technologies, the demand for LIDAR sensors has increased. The SWIR photodetector is a sensor that detects lasers for the 3D mapping of lidar sensor and is the most important technology of LIDAR sensor. An SWIR photodetector based on QDs in an eye-safe wavelength band of over 1400 nm has been reported. QDs-based SWIR photodetectors can be synthesized and processed through a solution process and have the advantages of low cost and simple processing. However, the organic ligands of QDs have insulating properties that limit their ability to improve the sensitivity and stability of photodetectors. Therefore, the technology to replace organic ligands with inorganic ligands must be developed. In this study, the organic ligand of the synthesized PbS QDs was replaced with a MAPI inorganic ligand, and an SWIR photodetector was fabricated. The analysis of the characteristics of the manufactured photodetector confirmed that the photodetector based on MAPI-capped PbS QDs exhibited up to 26.5% higher responsivity than that based on organic ligand PbS QDs.

3D 프린팅을 이용한 Pt/Carbon Nanotube composite 기반전기화학식 황화수소 가스 센서 제작

하윤태,권진범,최수지,정대웅 한국센서학회 2023 센서학회지 Vol.32 No.5

Among various types of harmful gases, hydrogen sulfide is a strong toxic gas that is mainly generated during spillageand wastewater treatment at industrial sites. Hydrogen sulfide can irritate the conjunctiva even at low concentrations of lessthan 10 ppm, cause coughing, paralysis of smell and respiratory failure at a concentration of 100 ppm, and coma and permanentbrain loss at concentrations above 1000 ppm. Therefore, rapid detection of hydrogen sulfide among harmful gasesis extremely important for our safety, health, and comfortable living environment. Most hydrogen sulfide gas sensors thathave been reported are electrical resistive metal oxide-based semiconductor gas sensors that are easy to manufacture andmass-produce and have the advantage of high sensitivity; however, they have low gas selectivity. In contrast, the electrochemicalsensor measures the concentration of hydrogen sulfide using an electrochemical reaction between hydrogen sulfide,an electrode, and an electrolyte. Electrochemical sensors have various advantages, including sensitivity, selectivity, fastresponse time, and the ability to measure room temperature. However, most electrochemical hydrogen sulfide gas sensorsdepend on imports. Although domestic technologies and products exist, more research is required on their long-term stabilityand reliability. Therefore, this study includes the processes from electrode material synthesis to sensor fabrication and characteristicevaluation, and introduces the sensor structure design and material selection to improve the sensitivity and selectivityof the sensor. A sensor case was fabricated using a 3D printer, and an Ag reference electrode, and a Pt counterelectrode were deposited and applied to a Polytetrafluoroethylene (PTFE) filter using PVD. The working electrode was alsodeposited on a PTFE filter using vacuum filtration, and an electrochemical hydrogen sulfide gas sensor capable of measuringconcentrations as low as 0.6 ppm was developed.

1-propanol 첨가에 따른 이산화타이타늄(TiO₂) 광 촉매의 비표면적 향상 및 이산화탄소 환원 효율 향상

하윤태,권진범,안희경,정대웅,Ha, Yuntae,Kwon, JinBeom,An, Heekyung,Jung, Daewoong 한국센서학회 2022 센서학회지 Vol.31 No.5

Recently, the problem of global warming caused by greenhouse gases is getting serious due to the development of industry and the increase in transportation means. Accordingly, the need for a technology to reduce carbon dioxide, which accounts for most of the greenhouse gas, is increasing. Among them, a catalyst for converting carbon dioxide into fuel is being actively studied. Catalysts for reducing carbon dioxide are classified into thermal catalysts and photocatalysts. In particular, the photocatalyst has the advantage that carbon dioxide can be reduced only by irradiating ultraviolet rays at room temperature without high temperature or additional gas. TiO₂ is widely used as a photocatalyst because it is non-toxic and has high stability, but has a disadvantage of low carbon dioxide reduction efficiency. To increase the reduction efficiency, 1-propanol was used in the synthesis process. This prevents agglomeration of the catalyst and increases the specific surface area and pores of TiO₂, thereby increasing the surface area in contact with carbon dioxide. As a result of measuring the CO₂ reduction efficiency, it was confirmed that the efficiency of TiO₂ with 1-propanol and TiO₂ without 1-propanol was 19% and 12.3%, respectively, and the former showed a 1.5 times improved efficiency.

Pt/CNT 전극 기반 전기화학식 센서의 전해질에 따른 황화수소 감지 특성

하윤태,정대웅,권진범,최수지,백수빈 한국센서학회 2023 센서학회지 Vol.32 No.3

With the recent development of industrial technology, the problem of odor due to leakage of toxic gas discharged from industrial complexes is gradually increasing. Among them, hydrogen sulfide is a colorless representative odorous substance that can cause pain through irritation of the mucous membranes of the eyes and respiratory tract, and is a gas that can cause central nervous system paralysis and suffocation when exposed to high concentrations. Therefore, in order to improve the odor problem, research on a gas sensor capable of quickly and reliably detecting a leak of hydrogen sulfide is being actively conducted. A lot of research has been done on the existing metal oxide-based hydrogen sulfide gas sensor, but it has the disadvantage of requiring low selectivity and high temperature operating conditions. Therefore, in this study, a Pt/CNT-based electrochemical hydrogen sulfide gas sensor capable of detecting at low temperatures with high selectivity for hydrogen sulfide was developed. A working electrode capable of selectively detecting only hydrogen sulfide was fabricated by synthesizing Pt nanoparticles as a catalyst on functionalized CNT and applied to an electrochemical hydrogen sulfide gas sensor. It was confirmed that the manufactured Pt/CNT-based electrochemical hydrogen sulfide gas sensor has a current change of up to 100uA for hydrogen sulfide, and the both response time and recovery time were within 15 seconds.

황화납 양자점 감지막을 통해 감도가 개선된 수소센서

김세완,김나리,권진범,김재건,정동건,공성호,정대웅 한국센서학회 2020 센서학회지 Vol.29 No.6

In this study, a PbS quantum dots (QDs)-based H2 gas sensor with a Pd electrode was proposed. QDs have a size of several nanometers, and they can exhibit a high surface area when forming a thin film. In particular, the NH2 present in the ligand of PbS QDs and H2 gas are combined to form NH3+, subsequently the electrical characteristics of the QDs change. In addition to the resistance change owing to the reaction between Pd and H2 gas, the resistance change owing to the reaction between the NH2 of PbS QDs and H2 gas increases the current signal at the sensor output, which can produce a high output signal for the same concentration of H2 gas. Using the XRD and absorbance properties, the synthesis and particle size of the synthesized PbS QDs were analyzed. Using PbS QDs, the sensitivity was significantly improved by 44%. In addition, the proposed H2 gas sensor has high selectivity because it has low reactivity with heterogeneous gases such as C2H2, CO2, and CH4.

열처리 효과에 따른 SnO2 기반 수소가스 센서의 특성 최적화

정동건,정대웅,이준엽,권진범,맹보희,김영삼,양이준 한국센서학회 2022 센서학회지 Vol.31 No.5

Hydrogen gas (H2) which is odorless, colorless is attracting attention as a renewable energy source in varions applications but its leakage can lead to disastrous disasters, such as inflammable, explosive, and narcotic disasters at high concentrations. Therefore, it is necessary to develop H2 gas sensor with high performance. In this paper, we confirmed that H2 gas detection ability of SnO2 based H2 gas sensor along with thermal treatment effect of SnO2. Proposed SnO2 based H2 gas sensor is fabricated by MEMS technologies such as photolithgraphy, sputtering and lift-off process, etc. Deposited SnO2 thin films are thermally treated in various thermal treatement temperature in range of 500–900oC and their H2 gas detection ability is estimatied by measuring output current of H2 gas sensor. Based on experimental results, fabricated H2 gas sensor with SnO2 thin film which is thermally treated at 700oC has a superior H2 gas detection ability, and it can be expected to utilize at the practical applications.

황화납 양자점 기반의 인체 안정성 단파장 적외선 센서 개발

하윤태(Yuntae Ha),권진범(Jinbeom Kwon),최수지(SuJi Choe),정동건(Donggeon Jung),정대웅(Daewoong Jung) 한국생산제조학회 2023 한국생산제조시스템학회 학술발표대회 논문집 Vol.2023 No.12