Recent advances in two-dimensional photovoltaic devices

Two-dimensional(2D)materials have attracted tremendous interest in view of the outstanding optoelectronic properties,showing new possibilities for future photovoltaic devices toward high performance,high specific power and flexibility.In recent years,substantial works have focused on 2D photovoltaic devices,and great progress has been achieved.Here,we present the review of recent advances in 2D photovoltaic devices,focusing on 2D-material-based Schottky junctions,homojunctions,2D−2D heterojunctions,2D−3D heterojunctions,and bulk photovoltaic effect devices.Furthermore,advanced strategies for improving the photovoltaic performances are demonstrated in detail.Finally,conclusions and outlooks are delivered,providing a guideline for the further development of 2D photovoltaic devices.

Ion Migration and Accumulation in Halide Perovskite Solar Cells

Comprehensive Summary The halide perovskite semiconductors-based solar cells(PVSCs)show great promise as next-generation renewable energy sources,with the merits of low cost,high performance,good flexibility,etc.A major difference distinguishing the perovskite semiconductors from others lies in their ionic feature.This intrinsic property induces“freely-moving”ions to migrate and accumulate in the perovskite films and devices under different external stresses.As a charge carrier,these processes will strongly couple with the electronic process,and dramatically affect the performance and stability of PVSCs.This review summarizes and discusses the recent progresses and fundamental understandings of ion migration and accumulation behaviors in PVSCs.First,the basic principles of the general ion migration are reviewed.Second,following the fundamental understandings,the critical factors,e.g.,ion migration activation energy,ion density,ion diffusion coefficient,etc.,are extracted to understand the ion migration and accumulation in perovskite film.Third,the principles governing ion accumulation behaviors under different external stresses are discussed.Finally,the effect of ion migration and accumulation on band bending,and device performance is presented.Therefore,we hope this review provides a tutorial and insightful perspective regarding the most prominent ionic feature of perovskite semiconductors and their application for photovoltaics.

IFE based nanosensor composed of UCNPs and Fe(Ⅱ)-phenanthroline for detection of hypochlorous acid and periodic acid

Oxidizing CIO^(-)and IO_(4)^(-)exist widely in environment and are closely related to the health of organisms.Accordingly,fast,sensitive,and direct detection of the two species is significant.Using IFE in UCNPs@PAA and Fe(Ⅱ)-phenanthroline system,an elegant ratiometric fluorescent nanosensor,without noble metal nanoparticle,was designed for the detection of CIO-and IO4-.Fe(Ⅱ)-phenanthroline complex is used as fluorescent absorber,which can quench green light of UCNPs with gradually varied extent depending on the concentration of Fe(Ⅱ).The linear zone extends to 800 and 120μmol/L while the detection limit is 1.30 and 0.58μmol/L for NaCIO and NaIO_(4),respectively.Finally,the nanosensor was successfully applied to detect NaCIO and NaIO4spiked in milk,spring water,and tap water with good recoveries.

张承志回族小说的伊斯兰情结研究

张承志回族作家的身份加之他所受到的多元文化的影响无疑使得他成为了中国当代文坛的一个独特存在,这些经历在不同的时期对他产生了不同的影响,同时又相互碰撞摩擦,共同造就出了一位思想自由、人格独立、具有民族气质、充满血性的当代文学作家。

具有亚2-nm沟道长度的二维垂直p-n结二极管

尺寸极限微缩的p-n结二极管对互补金属氧化物半导体(CMOS)集成电路的发展至关重要.然而,由于界面缺陷和短沟道效应,实现5 nm以下沟道长度的p-n结二极管仍然面临着巨大的挑战.本文展示了1.9 nm沟道的WSe_(2)/WS_(2)垂直p-n结二极管,实现了~8×10^(3)的高开关比和~17的整流比.此外,沟道长度为4.7 nm的器件具有~10^(4)的高开关比和~10^(3)的整流比.其高性能源于无肖特基势垒的接触导致的理想带排列,以及无缺陷的全范德华(vdW)界面导致的低隧穿电流和小的费米钉扎效应.因此,我们实现了p-n二极管的本征性能.该策略也可以扩展到其他的p-n结,如WSe_(2)/MoSe_(2)和WSe_(2)/MoS_(2),这表明我们的策略具有普适性.该策略为电子器件尺寸微缩和集成电路的进一步发展提供了新的思路.