Doped p–n junctions are fundamental electrical components in modern electronics and optoelectronics. Due to the development of device miniaturization, the emergence of two‐dimensional (2D) materials may initiate the next technological leap toward the post‐Moore era owing to their unique structures and physical properties. The purpose of fabricating 2D p–n junctions has fueled many carrier‐type modulation methods, such as electrostatic doping, surface modification, and element intercalation. Here, by using the nonvolatile ferroelectric field polarized in the opposite direction, efficient carrier modulation in ambipolar molybdenum telluride (MoTe2) to form a p–n homojunction at the domain wall is demonstrated. The nonvolatile MoTe2 p–n junction can be converted to n–p, n–n, and p–p configurations by external gate voltage pulses. Both rectifier diodes exhibited excellent rectifying characteristics with a current on/off ratio of 5 × 105. As a photodetector/photovoltaic, the device presents responsivity of 5 A W−1, external quantum efficiency of 40%, specific detectivity of 3 × 1012 Jones, fast response time of 30 µs, and power conversion efficiency of 2.5% without any bias or gate voltages. The MoTe2 p–n junction presents an obvious short‐wavelength infrared photoresponse at room temperature, complementing the current infrared photodetectors with the inadequacies of complementary metal‐oxide‐semiconductor incompatibility and cryogenic operation temperature.

Van der Waals integration with abundant two-dimensional materials provides a broad basis for assembling functional devices. In a specific van der Waals heterojunction, the band alignment engineering is crucial and feasible to realize high performance and multifunctionality. Here, we design a ferroelectric-tuned van der Waals heterojunction device structure by integrating a GeSe/MoS2 VHJ and poly (vinylidene fluoride-trifluoroethylene)-based ferroelectric polymer. An ultrahigh electric field derived from the ferroelectric polarization can effectively modulate the band alignment of the GeSe/MoS2 heterojunction. Band alignment transition of the heterojunction from type II to type I is demonstrated. The combination of anisotropic GeSe with MoS2 realizes a high-performance polarization-sensitive photodetector exhibiting low dark current of approximately 1.5 pA, quick response of 14 μs, and high detectivity of 4.7 × 1012 Jones. Dichroism ratios are also enhanced by ferroelectric polarization in a broad spectrum from visible to near-infrared. The ferroelectric-tuned GeSe/MoS2 van der Waals heterojunction has great potential for multifunctional detection applications in sophisticated light information sensing. More profoundly, the ferroelectric-tuned van der Waals heterojunction structure provides a valid band-engineering approach to creating versatile devices.

The advent of low-dimensional materials with peculiar structure and superb band properties provides a new canonical form for the development of photodetectors. However, the limited exploitation of basic properties makes it difficult for devices to stand out. Here, we demonstrate a hybrid heterostructure with ultrathin vanadium dioxide film and molybdenum ditelluride nanoflake. Vanadium dioxide is a classical semiconductor with a narrow bandgap, a high temperature coefficient of resistance, and phase transformation. Molybdenum ditelluride, a typical two-dimensional material, is often used to construct optoelectronic devices. The heterostructure can realize three different functional modes: (i) the p–n junction exhibits ultrasensitive detection (450 nm–2 μm) with a dark current down to 0.2 pA and a response time of 17 μs, (ii) the Schottky junction works stably under extreme conditions such as a high temperature of 400 K, and (iii) the bolometer shows ultrabroad spectrum detection exceeding 10 μm. The flexible switching between the three modes makes the heterostructure a potential candidate for next-generation photodetectors from visible to longwave infrared radiation (LWIR). This type of photodetector combines versatile detection modes, shedding light on the hybrid application of novel and traditional materials, and is a prototype of advanced optoelectronic devices.

MoS2, one of the most valued 2D materials beyond graphene, shows potential for future applications in postsilicon digital electronics and optoelectronics. However, achieving hole transport in MoS2, which is dominated by electron transport, is always a challenge. Here, MoS2 transistors gated by electrolyte gel exhibit the characteristics of hole and electron transport, a high on/off ratio over 105, and a low subthreshold swing below 50 mV per decade. Due to the electrolyte gel, the density of electrons and holes in the MoS2 channel reaches ≈9 × 1013 and 8.85 × 1013 cm−2, respectively. The electrolyte gel‐assisted MoS2 phototransistor exhibits adjustable positive and negative photoconductive effects. Additionally, the MoS2 p–n homojunction diode affected by electrolyte gel shows high performance and a rectification ratio over 107. These results demonstrate that modifying the conductance of MoS2 through electrolyte gel has great potential in highly integrated electronics and optoelectronic photodetectors.