Band alignment study of 2D-2D heterointerface of MoSe2 with Ti3C2Tx (transport layer) for flexible broadband photodetection

This work signifies the band alignment study of solution processed MoSe2 with MXene (Ti3C2Tx) using Ultraviolet Photoelectron Spectroscopy and utilizing the same for broadband photodetection. Based on the work function values calculated from ultraviolet photoelectron spectroscopy (UPS), MXene functions as an excellent transport layer for the photogenerated excitons generated in MoSe2. Due to the wideband absorbance of MoSe2, the photodetection experiments were carried out from the visible to NIR range (554 nm–780 nm). To examine the heterointerface's band alignment and carrier migration mechanism between MoSe2 and MXene, work function values were extracted from UPS and used to understand the actual energy band diagram of the MoSe2/MXene interface. The fabricated MoSe2/MXene photodetector exhibits Responsivity of 6.58 mA/W and 9.82 mA/W for visible and NIR light illumination supporting that the fabricated device has a high response to the NIR spectrum due to its high absorption at NIR light incidence. The durability of the MoSe2/MXene photodetector was tested four times by examining the device response, wherein change in the Responsivity values was observed to be negligible. Understanding the band alignment of heterostructure through proper extraction of the work function values from UPS is a step ahead in choosing perfect materials for photodetection and optoelectronic applications.