(257b) Metal-Organic Frameworks Coated Opto-Electronic Gas Sensor Incorporated with Copper Sulfide Nanostructured Thin Films

Near-infrared (NIR) gas sensing is an important technique that requires simple operation and low cost with high accuracy and quick response. However, the absorption band of gases at NIR region is typically low; therefore it is urgent to develop a new concept of sensing technology with high sensitivity. Low-cost materials consist of earth-abundant elements such as copper sulfide (Cu_xS) exhibit localized surface plasmon resonance (LSPR) throughout the NIR region and can be used as LSPR-based sensing material. In this work, Cu_xS thin films were fabricated by a modified successive ionic layer adsorption and reaction at room temperature. Dense and uniform Cu_xS thin films were obtained through low temperature annealing process in air. The annealed Cu_xS films showed nanoflake-shape and excellent opto-electrical properties that we could explore in the gas-sensing field. LSPR absorption is able to control by tuning the composition of Cu_xS. By introducing a thin layer of nanoporous material, metal-organic frameworks (MOFs), onto the surface of Cu_xS thin films, gas molecules can be concentrated within the LSPR field. The fabricated nano-composite films show an enhancement of CO₂ absorption in NIR region compared to that of samples with only one type of film. Interestingly, the I-V test results showed that the conductivity of Cu_xS films was decreased with the existence of CO₂ molecules. Based on our findings, MOF coated Cu_xS films can serve as an opto-electronic gas sensor in the NIR region.