A photodetector based on the non-centrosymmetric 2D pseudo-binary chalcogenide MnIn₂Se₄

Due to their attractive band gap properties and van der Waals structure, 2D binary chalcogenide materials have been widely investigated in the last decade, finding applications in several fields such as catalysis, spintronics, and optoelectronics. Ternary 2D chalcogenide materials are a subject of growing interest in materials science due to their superior chemical tunability which endows tailored properties to the devices prepared thereof. In the family of A^IIB^III ₂X^VI ₄, ordered ZnIn₂S₄-like based photocatalytic systems have been studied meticulously. In contrast, reports on disordered phases appear to a minor extent. Herein, a photoelectrochemical (PEC) detector based on the pseudo-binary MnIn₂Se₄ system is presented. A combination of optical measurements and DFT calculations confirmed that the nature of the bandgap in MnIn₂Se₄ is indirect. Its performance outclasses that of parent compounds, reaching responsivity values of 8.41 mA W^-1. The role of the non-centrosymmetric crystal structure is briefly discussed as a possible cause of improved charge separation of the photogenerated charge carriers.