Tunable Infrared Sensing Properties of MXenes Enabled by Intercalants

摘要

Light interaction physical properties of MXenes are fundamentally importantand promising for developing new broadband photodetection applications.In this work, the significant influence of intercalants on the photo-electronicproperties of MXenes is studied. It is found that the intercalated H_2O-inducedinter-flake resistance greatly restricts the photon excitation responsivity ofTi_3C_2T_x, resulting in a slow and irreversible resistance change under laserirradiation. After deintercalation of H_2O by in situ laser writing, the resistanceof Ti_3C_2T_x responds fast and reversibly to laser excitation and the variationrange is proportional to laser power. By extending the findings to anotherMXene member, Mo_2TiC_2, the intercalant induced resistance is successfullydeveloped for optoelectronic detection. By selectively deintercalating H_2O inthe as-prepared Mo_2TiC_2 which is co-intercalated by H_2O and TMAOH, bareTMAOH intercalated Mo_2TiC_2 shows fast and reversible resistance changeswith laser. Moreover, the resistance of bare TMAOH intercalated Mo_2TiC_2shows a negative temperature coefficient behavior while the fully deintercalatedTi_3C_2T_x shows a positive temperature behavior. These findings elucidatethe understanding of the optoelectronic properties of Mxenes and provideinsights into the engineering of interfacial chemistry of Mxenes for performanceenhancement toward various detectors/sensors beyond optoelectronicapplications.