Plasmonic nanostructures have been widely incorporated into different semiconductor materials to improve solar energy conversion. An important point is how to manipulate the incident light so that more light can be efficiently scattered and absorbed within the semiconductors. Here, by using a tunable three-dimensional Au pillar/truncated-pyramid (PTP) array as a plasmonic coupler, a superior optical absorption of about 95% within a wide wavelength range is demonstrated from an assembled CdS/Au PTP photoanode. Based on incident photon to current efficiency measurements and the corresponding finite difference time domain simulations, it is concluded that the enhancement is mainly attributed to an appropriate spectral complementation between surface plasmon resonance modes and photonic modes in the Au PTP structure over the operational spectrum. Because both of them are wavelength-dependent, the Au PTP profile and CdS thickness are further adjusted to take full advantage of the complementary effect, and subsequently, an angle-independent photocurrent with an enhancement of about 400% was obtained. The designed plasmonic PTP nanostructure of Au is highly robust, and it could be easily extended to other plasmonic metals equipped with semiconductor thin films for photovoltaic and photoelectrochemical cells.

over decades. Oxychalcogenides, which can be regarded as mixing and bridging chalcogenides and oxides together, reactivate their research booms for the remarkable phenomena such as high carrier mobility, [9] thermoelectricity, [10][11][12] ferroelectricity, [13] and superconductivity. [14] Bi 2 O 2 Se, a representative of oxychalcogenides family, emerged as an air-stable highmobility layered semiconductor, which holds promise for next-generation digital devices and optoelectronics. [2,9,13,[15][16][17][18][19][20][21][22][23] For example, the bulk Bi 2 O 2 Se crystals show an ultrahigh Hall mobility of ≈280 000 cm 2 V −1 s −1 at low temperature [9] and robust bandgap (immune to Se vacancies) after cleavage. [17] Nanoplates and thin films of Bi 2 O 2 Se were successfully prepared by chemical vapor deposition (CVD), [9,15,21,23] displaying excellent switching behavior of I on /I off and high Hall mobility (up to 450 cm 2 V −1 s −1 ) at room temperature. Outstanding optoelectronic properties were recently observed in CVD-grown Bi 2 O 2 Se nanoplates. [16,18,[23][24][25] The present research is mainly focused on the bulk crystals and few-layer or multiplayer samples due to the challenge to faithfully achieve the growth of atomically thin Bi 2 O 2 Se films. The atomically thin counterpart down to one-unit-cell (1-UC) Atomically thin oxychalcogenides have been attracting intensive attention for their fascinating fundamental properties and application prospects. Bi 2 O 2 Se, a representative of layered oxychalcogenides, has emerged as an air-stable high-mobility 2D semiconductor that holds great promise for next-generation electronics. The preparation and device fabrication of high-quality Bi 2 O 2 Se crystals down to a few atomic layers remains a great challenge at present. Here, molecular beam epitaxy (MBE) of atomically thin Bi 2 O 2 Se films down to monolayer on SrTiO 3 (001) substrate is achieved by co-evaporating Bi andSe precursors in oxygen atmosphere. The interfacial atomic arrangements of MBE-grown Bi 2 O 2 Se/SrTiO 3 are unambiguously revealed, showing an atomically sharp interface and atom-to-atom alignment. Importantly, the electronic band structures of one-unit-cell (1-UC) thick Bi 2 O 2 Se films are observed by angle-resolved photoemission spectroscopy (ARPES), showing low effective mass of ≈0.15 m 0 and bandgap of ≈0.8 eV. These results may be constructive to the synthesis of other 2D oxychalcogenides and investigation of novel physical properties. Ultrathin FilmsThanks to their rich physics and fascinating application prospects, atomically thin metal oxides/chalcogenides (sulfide, selenide, or telluride) and their heterostructures, such as transition metal dichalcogenides (TMDs), [1,2] superconducting β-phase FeSe, [3,4] topological insulator (Bi 2 Se 3 , Bi 2 Te 3 ), [5,6] and LaAlO 3 /SrTiO 3 , [7,8] have been attracting tremendous interest

The fast development of high-resolution electron microscopy (EM) demands a backgroundnoise-free substrate to support the specimens, where atomically thin graphene membranes can serve as an ideal candidate. Yet the preparation of robust and ultraclean graphene EM grids remains challenging. Here we present a polymer-and transfer-free direct-etching method for batch fabrication of robust ultraclean graphene grids through membrane tension modulation. Loading samples on such graphene grids enables the detection of single metal atoms and atomic-resolution imaging of the iron core of ferritin molecules at both room-and cryo-temperature. The same kind of hydrophilic graphene grid allows the formation of ultrathin vitrified ice layer embedded most protein particles at the graphene-water interface, which facilitates cryo-EM 3D reconstruction of archaea 20S proteasomes at a record high resolution of~2.36 Å. Our results demonstrate the significant improvements in image quality using the graphene grids and expand the scope of EM imaging.

The formation of heterojunction within solid‐state devices enables them with eventually high performances, but provides a challenge for material synthesis and device fabrication because strict conditions such as lattice match are needed. Herein, we show a facile method to fabricate a van der Waals (vdW) heterojunction between two‐dimensional (2D) bismuth oxyselenide (Bi2O2Se) and graphene, during which the graphene is directly transferred to the Bi2O2Se and served as a low‐contract‐resistant electrode with small work function mismatch (~50 meV). As an optoelectronic device, the Bi2O2Se/graphene vdW heterojunction allows for the efficient sensing toward 1200‐nm incident laser. Regarding the application of field‐effect transistors (FETs), the short‐channel (50 nm) sample can be synthesized by utilizing these two 2D materials (ie, channel: Bi2O2Se; drain/source terminal: graphene) and the n‐type characteristic can be observed with the accordant field modulation. It is confirmed that we show a simple way to prepare the vdW heterojunction which is aiming to the high‐performance applications among optoelectronics and FETs.