Owing to enhanced charge transport efficiency arising from the ultrathin nature, two-dimensional (2D) organic semiconductor single crystals (OSSCs) are emerging as a fascinating platform for high-performance organic field-effect transistors (OFETs). However, "coffee-ring" effect induced by an evaporation-induced convective flow near the contact line hinders the large-area growth of 2D OSSCs through a solution process. Here, we develop a new strategy of suppressing the "coffee-ring" effect by using an organic semiconductor: polymer blend solution. With the high-viscosity polymer in the organic solution, the evaporation-induced flow is remarkably weakened, ensuring the uniform molecule spreading for the 2D growth of the OSSCs. As an example, wafer-scale growth of crystalline film consisting of few-layered 2,7-didecylbenzothienobenzothiophene (C₁₀-BTBT) crystals was successfully accomplished via blade coating. OFETs based on the crystalline film exhibited a maximum hole mobility up to 12.6 cm²·V^-1·s^-1, along with an average hole mobility as high as 8.2 cm²·V^-1·s^-1. Our work provides a promising strategy for the large-area growth of 2D OSSCs toward high-performance organic electronics.

Growth of two-dimensional (2D) organic single crystals (2DOSCs) on water surface has attracted increasing attention, because it can serve as a molecularly flat and defect-free substrate. However, large-area growth of 2DOSCs with controllable crystal orientation on water surface remains a key challenge. Herein, we develop a simple method, i.e. external-force-driven solution epitaxy (EFDSE), for the large-area growth of 2DOSCs at air/water interface. Using 2, 7-didecylbenzothienobenzothiophene (C10-BTBT) as an example, high-quality 2D C₁₀-BTBT crystals on centimeter scale are generated by directionally controlling the spreading of organic solution on water surface with external force. Benefiting from the controllable crystal orientation with optimal charge transport, the corresponding 2DOSC-based organic field-effect transistors (OFETs) exhibit a high carrier mobility of 13.5 cm²·V^-1·s^-1 (effective mobility ≈ 5.4 cm²·V^-1·s^-1 according to a reliability factor of 40%), which represents the best result achieved for water-surface-assembled 2DOSC-based OFETs. Furthermore, by transferring the C₁₀-BTBT 2DOSCs to flexible substrates, devices with excellent bending stability are achieved. It is anticipated that our method will provide new insight into the controllable growth of large-area 2DOSCs for high-performance organic devices.

Silicon nanowire (SiNW) fabrics are of great interest for fabricating high-performance multifunctional wearable sensors. However, it remains a big challenge to fabricate high-quality SiNW fabrics in a simple and efficient manner. Here we report, for the first time, one-step growth of large-area SiNW fabrics for multifunctional wearable sensors, by using a massive metal-assisted chemical vapor deposition (CVD) method. With bulk Sn as a catalyst source, numerous millimeter-long SiNWs grow and naturally interweave with each other, forming SiNW fabrics over 80 cm² in one experiment. In addition to intrinsic electronic properties of Si materials, the SiNW fabrics also feature high flexibility, good tailorability and light weight, rendering them ideal for fabricating multifunctional wearable sensors. The prototype sensors based on the SiNW fabrics could effectively detect various stimuli including temperature, light, strain and pressure, with outstanding performance among reported multifunctional sensors. We further demonstrate the integration of the prototype sensors onto the body of a robot, enabling its perception to various environmental stimuli. The ability to prepare high-quality SiNW fabrics in a simple and efficient manner will stimulate the development of wearable devices for applications in portable electronics, Internet of Things, health care and robotics.

Solution-processed n-type organic semiconductor micro/nanocrystals (OSMCs) are fundamental elements for developing low-cost, large-area, and all organic logic/complementary circuits. However, the development of air-stable, highly aligned n-channel OSMC arrays for realizing high-performance devices lags far behind their p-channel counterparts. Herein, we present a simple one-step slope-coating method for the large-scale, solution-processed fabrication of highly aligned, air-stable, n-channel ribbon-shaped single-crystalline N, N′-bis(2-phenylethyl)-perylene-3, 4:9, 10-tetracarboxylic diimide (BPE-PTCDI) arrays. The slope and patterned photoresist (PR) stripes on the substrate are found to be crucial for the formation of large-area submicron ribbon arrays. The width and thickness of the BPE-PTCDI submicron ribbons can be finely tuned by controlling the solution concentration as well as the slope angle. The resulting BPE-PTCDI submicron ribbon arrays possess an optimum electron mobility up to 2.67 cm²·V^–1·s^–1 (with an average mobility of 1.13 cm²·V^–1·s^–1), which is remarkably higher than that of thin film counterparts and better than the performance reported previously for single-crystalline BPE-PTCDI-based devices. Moreover, the devices exhibit robust air stability and remain stable after exposing in air over 50 days. Our study facilitates the development of air-stable, n-channel organic field-effect transistors (OFETs) and paves the way towards the fabrication of high-performance, organic single crystal-based integrated circuits.

As one of the most important semiconductor materials, silicon (Si) has been widely used in current energy and optoelectronic devices, such as solar cells and photodetectors. However, the traditional Si p–n junction solar cells need complicated fabrication processes, leading to the high cost of Si photovoltaic devices. The wide applications of Si-based photodetectors are also hampered by their low sensitivity to ultraviolet and infrared light. Recently, two-dimensional (2D) layered materials have emerged as a new material system with tremendous potential for future energy and optoelectronic applications. The combination of Si with 2D layered materials represents an innovative approach to construct high-performance optoelectronic devices by harnessing the complementary advantages of both materials. In this review, we summarize the recent advances in 2D layered material/Si heterojunctions and their applications in photovoltaic and optoelectronic devices. Finally, the outlook and challenges of 2D layered material/Si heterojunctions for high-performance device applications are presented.

We present an ultrasensitive ultraviolet (UV) detector based on a p-type ZnS nanoribbon (NR)/indium tin oxide (ITO) Schottky barrier diode (SBD). The device exhibits a pseudo-photovoltaic behavior which can allow the SBD to detect UV light irradiation with incident power of 6 × 10^-17 W (~85 photons/s on the NR) at room temperature, with excellent reproducibility and stability. The corresponding detectivity and photoconductive gain are calculated to be 3.1 × 10²⁰ cm·Hz^1/2·W^-1 and 6.6 × 10⁵, respectively. It is found that the presence of the trapping states at the p-ZnS NR/ITO interface plays a crucial role in determining the ultrahigh sensitivity of this nanoSBDs. Based on our theoretical calculation, even ultra-low photon fluxes on the order of several tens of photons could induce a significant change in interface potential and consequently cause a large photocurrent variation. The present study provides new opportunities for developing high-performance optoelectronic devices in the future.