data. [2] But as achieving highly miniaturized and integrated devices, the limit of Moore's law era is approaching. Because of their unique physicochemical properties, such as superior carrier mobility and high photoelectric conversion efficiency, two-dimensional (2D) materials have attracted attention to facilitate the performance improvement of photo detectors. [3] However, weak switching characteristics, limited wavelength detection, and instability have restrained applications of 2D materials. For example, ultra-broadband photodetectors using graphene [4] have zero bandgaps with no switching characteristics. [2,5] Graphene-like black phosphorus (BP) has a thickness-modulated direct bandgap from 0.3 eV (bulk) to 2 eV (monolayer), [6] but irreversible ambient oxidization greatly degrades its performance. [7] Transition-metal dichalcogenides (TMDs), such as MoS 2 , [8] MoSe 2 , [9] and WS 2 , [10] also have thickness-tunable bandgaps, [11] low dark currents, and relatively high carrier mobilities. [12] However, their limited bandgaps for solar-blind ultraviolet have become impediments. [13] Hence, materials with suitable switching characteristics, tunable bandgaps, high carrier mobilities, and robust stabilities under ambient conditions are urgently needed.Recently, metal phosphorus trichalcogenides (MPTs) with superior optical, electronic, magnetic, and catalytic properties have garnered tremendous interest because of their unique electronic structures and energy bands. [14] They have a common MPX 3 stoichiometry that spans many elements (M = Cr, Mn, Fe, Co, Ni, Zn or Cd; X = S or Se). The metal cations (M 2+ ) weakly bond the anion group bipyramids [P 2 X 6 ] 4− in a honeycomb structure, while the [P 2 X 6 ] 4− unit is formed by one P atom coordinated with three S (or Se) atoms. The distinctive MPT properties are derived from the electron number in the d orbital, or outermost shell, of the metal elements, and the high spin state of metal atoms resulting from the weak ligand field of the [P 2 X 6 ] 4− unit. [15] As a result, MnPSe 3 flakes have been reported to be a potential spintronic material because it can be transformed from an antiferromagnetic semiconductor to a ferromagnetic semi-metal via carrier doping. [16] Furthermore, the carrier mobility of MnPSe 3 approaches 625.9 cm 2 V −1 s −1 , [14a] which is higher than the aforementioned materials used in field-effect transistors (FETs, where BP has 275 cm 2 V −1 s −1 , [17] MoS 2 has > 200 cm 2 V −1 s −1 , [18] WSe 2 has 200 cm 2 V −1 s −1 [12c] , and WS 2 has 214 cm 2 V −1 s −1[12b] ). By varying the transition Photodetectors fabricated from very thin two-dimensional (2D) materials with high photoelectric conversion efficiency have unprecedented potential to overcome the limitations of conventional photodetectors. In particular, recent interest in 2D metal phosphorus trichalcogenides (MPTs) has derived from their strong light absorption, tunable bandgap, and robust stability. Here, large and atomically thin NiPS 3 flakes, prepared by electrochemical ...