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A unique charge‐injection‐narrowing organic photodetector (CIN OPD) is demonstrated for near‐infrared (NIR) range operation. In conventional CIN OPDs, photomultiplication (PM) is achieved within a bulk heterojunction (BHJ) active layer with a donor:acceptor ratio of 100:1. Unfortunately, this approach encounters an issue in which the narrowband detection wavelength is determined solely by an excessive donor quantity. Consequently, the conventional devices face a critical limitation in that their detection range cannot extend to longer wavelengths. However, this limitation has been overcome through a novel mechanism and have fabricated a device that responds at λ = 940 nm. When a perovskite quantum dot interlayer is inserted as the PM‐inducing layer, PM occurs outside the active layer. Therefore, the BHJ active layer is structured with a donor:acceptor ratio of 50:50, resulting in an extension of the detection wavelength to the absorption tail of the narrow‐bandgap acceptor. The device demonstrates a remarkable external quantum efficiency (EQE) of 39 000% with a narrow full‐width at half‐maximum (FWHM) of 98 nm at 60 V. It also has a high specific detectivity and a short response time. The device represents a significant advancement in filter‐free, high‐efficiency photodetectors suitable for optical sensor applications such as light detection and ranging (LiDAR). [ABSTRACT FROM AUTHOR]

Graphene is used as a growth template for van der Waals epitaxy of organic semiconductor (OSC) thin films. During the synthesis and transfer of chemical‐vapor‐deposited graphene on a target substrate, local inhomogeneities in the graphene—in particular, a nonuniform strain field in the graphene template—can easily form, causing poor morphology and crystallinity of the OSC thin films. Moreover, a strain field in graphene introduces a pseudo‐electric field in the graphene. Here, the study investigates how the strain and strain‐induced pseudo‐electric field of a graphene template affect the self‐assembly of π‐conjugated organic molecules on it. Periodically strained graphene templates are fabricated by transferring graphene onto an array of nanospheres and then analyzed the growth and nucleation behavior of C60 thin films on the strained graphene templates. Both experiments and a numerical simulation demonstrated that strained graphene reduced the desorption energy between the graphene and the C60 molecules and thereby suppressed both nucleation and growth of the C60. A mechanism is proposed in which the strain‐induced pseudo‐electric field in graphene modulates the binding energy of organic molecules on the graphene. [ABSTRACT FROM AUTHOR]

Although organic solar cells (OSCs) have received increasing attention because of their high device efficiencies, the fundamental mechanism governing their photostability remains elusive. Herein, the effect of the luminescence stability of the acceptor components on the burn‐in voltage loss of binary and ternary OSCs is demonstrated. A systematic characterization reveals that the acceptor component experiences an abnormal decrease in luminescence under photoaging—specifically, photoinduced luminescence quenching—because of a photoinduced conformational change. This phenomenon increases nonradiative recombination in blends and thus causes a substantial nonradiative voltage loss of OSCs. Moreover, an introduction of a third component with high luminescence stability can effectively reduce the burn‐in voltage loss of OSCs. A composition‐dependent photostability study of the resultant ternary OSCs reveals that the reduction in the burn‐in voltage loss of OSCs is mainly driven by the third component distributed in the mixed phase; high luminescence stability of this component effectively prevents the increase in nonradiative voltage loss by photoaging. The results suggest that improving the luminescence stability of the acceptor components can be an effective method for highly stable photovoltaics with greatly reduced burn‐in voltage loss. [ABSTRACT FROM AUTHOR]

A corona discharge treatment (CDT) is utilized to maximize the performance of triboelectric nanogenerators (TENGs) by injecting extra electrons into the negative tribomaterials. Increased performance of CDT TENGs, however, exhibits rapid degradation due to the electron dissipation by air moisture or thermal emission. To overcome such drawbacks and circumvent such dissipation, the source of charges should be replaced with ionic charges. This study reports a Ag nanowires (NWs)‐embedded laminating structure (AeLS) with a unique fabrication procedure for ionic charge injection by CDT. The injection of ions is achieved by interlayer‐CDT (i‐CDT), in which positive charges are dissipated by Ag NWs, and the opposite negative ions can remain on the outmost surface. The AeLS TENGs with i‐CDT exhibit high performance, long‐term stability, and durability. It shows voltage, current, and maximum power outputs of 380 V, 15 µA, and 827 mW m−2, respectively. As a practical demonstration, rotational TENG integrated with a direct discharge system is realized, and its current and voltage reach 7.4 mA and 7800 V, respectively. This work can pave the way for the design of ion‐based TENGs with high performance and long‐lasting retention of triboelectric charges. [ABSTRACT FROM AUTHOR]

Organometal halide perovskite (OHP) solar cells have been intensively studied because of their promising optoelectronic features, which has resulted in high power conversion efficiencies >23 %. Although OHP solar cells exhibit high power conversion efficiencies, their relatively poor stability is a significant obstacle to their practical use. We report that the chemical stability of OHP solar cells with respect to both moisture and heat can be improved by adding a small amount of Ag to the precursor. Ag doping increases the size of the OHP grains and reduces the size of the amorphous intergranular regions at the grain boundaries, and thereby hinders the infiltration of moisture into the OHP films and their thermal degradation. Quantum mechanical simulation reveals that Ag doping increases the energies of both the hydration reaction and heat‐induced vacancy formation in OHP crystals. This procedure also improves the power conversion efficiencies of the resulting solar cells. [ABSTRACT FROM AUTHOR]

Recent transistors are one of state‐of‐the‐art products of semiconductor industry. As it has been required to be minimized to the nanoscale regime, the classical model from the microelectronics is often challenged by its discrepancy. Therefore, understanding the behavior of electrons in such regime is essential for transistor applications in nanoscale. Herein, the charge trapping and anisotropic diffusion behaviors of electrons in multistacked nanostructures composed of a blocking oxide, a charge storage layer of Au nanoclusters (NCs), a tunneling oxide, and silicon substrate are reported. Electrons are injected from the substrate to Au NCs via quantum tunneling effect. The charge retention and diffusion characteristics of the NCs are investigated by measuring surface potential. To explore the spatial dependence, a line‐ and dot‐shaped injection of charges is examined. Both of the accumulated electrons decay following an exponential function of time. However, the injected electrons with a line‐shape in Au NCs are found to have a larger time constant than those with a dot‐shape. This result implies that the initial spatial distribution of electrons plays a role in determining the equilibrium distribution of the charges in the nanostructure. [ABSTRACT FROM AUTHOR]