Growing interest in hybrid organic-inorganic lead halide perovskites has led to the development of various perovskite nanowires (NWs), which have potential use in a wide range of applications, including lasers, photodetectors, and light-emitting diodes (LEDs). However, existing nanofabrication approaches lack the ability to control the number, location, orientation, and properties of perovskite NWs. Their growth mechanism also remains elusive. Here, we demonstrate a micro/nanofluidic fabrication technique (MNFFT) enabling both precise control and in situ monitoring of the growth of perovskite NWs. The initial nucleation point and subsequent growth path of a methylammonium lead iodide-dimethylformamide (MAPbI·DMF) NW array can be guided by a nanochannel. In situ UV-vis absorption spectra are measured in real time, permitting the study of the growth mechanism of the DMF-mediated crystallization of MAPbI. As an example of an application of the MNFFT, we demonstrate a highly sensitive MAPbI-NW-based photodetector on both solid and flexible substrates, showing the potential of the MNFFT for low-cost, large-scale, highly efficient, and flexible optoelectronic applications.

Topological crystalline insulator SnTe film/Si heterostructure were fabricated, which can function as self-driven, ultrafast and broadband photovoltaic detectors.

Electron injection plays a crucial role in arousing the double‐slope characteristics for p‐type organic field‐effect transistors (OFETs) with narrow‐bandgap organic semiconductors (OSCs). This issue will not only result in the misrepresentation of OFET performance but also may cause device instability, hence impeding their further development in real‐world applications. A facile and highly efficient approach is developed to circumvent this issue by implementing modification on the electrode/organic semiconductor interface. An ultrathin layer of wide‐bandgap OSC with suitable energy levels is introduced to block the undesirable electron injection. By this means, typical double‐slope behaviors and bias stress stability in the p‐type OFETs can be significantly improved. Using 2,8‐difluoro‐5,11‐bis(triethylsilylethynyl) anthradithiophene‐based OFETs the double‐slope behaviors of as‐fabricated devices are effectively converted to near‐ideal behaviors after modification, leading to a dramatic improvement of average reliability from 65.11% to 91.76%. Furthermore, the positive drift of transfer curves under prolonged bias stress is also successfully suppressed. This strategy demonstrates good universality and can provide a new guideline for the fabrication of OFETs with ideal behaviors.

Monolayer organic crystals have attracted considerable attention due to their extraordinary optoelectronic properties. Solution self‐assembly on the surface of water is an effective approach to fabricate monolayer organic crystals. However, due to the difficulties in controlling the spreading of organic solution on the water surface and the weak intermolecular interaction between the organic molecules, large‐area growth of monolayer organic crystals remains a great challenge. Here, a graphene quantum dots (GQDs)‐induced self‐assembly method for centimeter‐sized growth of monolayer organic crystals on a GQDs solution surface is reported. The spreading area of the organic solution can be readily controlled by tuning the pH value of the GQDs solution. Meanwhile, the π–π stacking interaction between the GQDs and the organic molecules can effectively reduce the nucleation energy of the organic molecules and afford a cohesive force to bond the crystals, enabling large‐area growth of monolayer organic crystals. Using 2,7‐didecyl benzothienobenzothiopene (C10‐BTBT) as an examples, centimeter‐sized monolayer C10‐BTBT crystal with uniform molecular packing and crystal orientation is attained. Organic field‐effect transistors based on the monolayer C10‐BTBT crystals exhibit a high mobility up to 2.6 cm2 V−1 s−1, representing the highest mobility value for solution‐assembled monolayer organic crystals. This work provides a feasible route for large‐scale fabrication of monolayer organic crystals toward high‐performance organic devices.

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Organic field-effect transistors (OFETs) often deviate from ideal behaviors in air, which masks their intrinsic properties and thus significantly impedes their practical applications. A key issue of how the presence of air affects the ideality of OFETs has not yet been fully understood. It is revealed that air atmosphere may exert a double-edged sword effect on the active semiconductor layer when determining the ideality of OFETs fabricated from p-type crystalline organic semiconductors. Upon exposing the as-fabricated device to air, water and oxygen mainly function as efficient p-type dopants for the active layer in the contact regions, enhancing charge carrier injection and consequently improving device ideality. Nevertheless, as the exposure time increases, the trapping centers for the injected minority charge carriers appear in the channel region, leading to degradation of device ideality. Inspired by the double-edged sword behavior of air, a near-ideal OFET is achieved by ingeniously utilizing the doping/positive effect and eliminating the trapping/negative effect. The effect of air on the ideality of p-type OFETs is clarified, which not only illuminates some common observations of OFETs in air but also offers useful guidance for the construction of high-performance ideal OFETs.

The roles of interfaces in determining the ideality of organic field-effect transistors (OFETs) are comprehensively summarized.

Being able to probe the polarization states of light is crucial for applications from medical diagnostics and intelligent recognition to information encryption and bio-inspired navigation. Current state-of-the-art polarimeters based on anisotropic semiconductors enable direct linear dichroism photodetection without the need for bulky and complex external optics. However, their polarization sensitivity is restricted by the inherent optical anisotropy, leading to low dichroic ratios of typically smaller than ten. Here, we unveil an effective and general strategy to achieve more than 2,000-fold enhanced polarization sensitivity by exploiting an anisotropic charge trapping effect in organic phototransistors. The polarization-dependent trapping of photogenerated charge carriers provides an anisotropic photo-induced gate bias for current amplification, which has resulted in a record-high dichroic ratio of >104, reaching over the extinction ratios of commercial polarizers. These findings further enable the demonstration of an on-chip polarizer-free bionic celestial compass for skylight-based polarization navigation. Our results offer a fundamental design principle and an effective route for the development of next-generation highly polarization-sensitive optoelectronics.