A Simple Building Block with Noncovalently Conformational Locks towards Constructing Low-Cost and High-Performance Nonfused Ring Electron Acceptors

Nonfused ring electron acceptors(NFREAs)have attracted much attention due to their concise synthetic routes and low cost.However,developing high-performance NFREAs with simple structure remains a great challenge.In this work,a simple building block(POBT)with noncovalently conformational locks(No CLs)was designed and synthesized.Single-crystal X-ray study indicated the presence of S…O NOCLs in POBT,thus enabling it to possess a coplanar conformation comparable to that of fused-ring CPT.Two novel NFREAs based on CPT and POBT were developed,namely TT-CPT and TT-POBT,respectively.Besides,TT-POBT possessed a smaller Stokes shift and a reduced reorganization energy compared with TT-CPT,indicating the introduction of S…O No CLs can enhance the molecular rigidity even if simplifying the molecular structure.As a result,the TT-POBT-based PSC device afforded an impressive power conversion efficiency of 11.15%,much higher than that of TT-CPT counterpart(7.03%),mainly resulting from the tighterπ-πstacking,improved and balanced charge transport,and more favorable film morphology.This work demonstrates the potential of the simple building block POBT with No CLs towards constructing low-cost and highperformance NFREAs.

Moiréflat bands of twisted few-layer graphite

We report that the twisted few layer graphite(tFL-graphite)is a new family of moiréheterostructures(MHSs),which has richer and highly tunable moiréflat band structures entirely distinct from all the known MHSs.A tFL-graphite is composed of two few-layer graphite(Bernal stacked multilayer graphene),which are stacked on each other with a small twisted angle.The moiréband structure of the tFL-graphite strongly depends on the layer number of its composed two van der Waals layers.Near the magic angle,a tFL-graphite always has two nearly flat bands coexisting with a few pairs of narrowed dispersive(parabolic or linear)bands at the Fermi level,thus,enhances the DOS at EF.This coexistence property may also enhance the possible superconductivity as been demonstrated in other multiband superconductivity systems.Therefore,we expect strong multiband correlation effects in tFL-graphite.Meanwhile,a proper perpendicular electric field can induce several isolated nearly flat bands with nonzero valley Chern number in some simple tFL-graphites,indicating that tFL-graphite is also a novel topological flat band system.

Doubled Moiré fat bands in double-twisted few-layer graphite

We study the electronic structure of double-twisted few-layer graphite(DTFLG),which consists of three few-layer graphites(FLGs),i.e.,an ABA-stacked graphene multilayer,stacked with two twist angles.We consider two categories of DTFLG,the alternately and chirally twisted cases,according to the rotation direction of the two twist angles.We show that,once the middle FLG of DTFLG is not thinner than the trilayer,both types of DTFLG can remarkably host two pairs of degenerate Moire flat bands(MFBs) at EF,twice that of the magic angle twisted bilayer graphene(TBG).The doubled MFBs of DTFLG lead to a doubled density of states(DOS) at the Fermi level EF,which implies much stronger correlation effects than TBG.The degeneracy of MFBs can be lifted by a perpendicular electric field,and the isolated MFBs have a nonzero valley Chern number.We also reveal the peculiar wave function patterns of the MFB s in DTFLG.Our results establish a new family of Moire systems that have a much higher DOS at EFand thus possibly much stronger correlation effects.

Flat band localization due to self-localized orbital

We discover a new wave localization mechanism in a periodic wave system,which can produce a novel type of flat band and is distinct from the known localization mechanisms,i.e.,Anderson localization and flat band lattices.The first example we give is a designed electron waveguide(EWG)on 2DEG with special periodic confinement potential.Numerical calculations show that,with proper confinement geometry,electrons can be completely localized in an open waveguide.We interpret this flat band localization(FBL)phenomenon by introducing the concept of self-localized orbitals.Essentially,each unit cell of the waveguide is equivalent to an artificial atom,where the self-localized orbital is a special eigenstate with unique spatial distribution.These self-localized orbitals form the flat bands in the waveguide.Such self-localized orbital induced FBL is a general phenomenon of wave motion,which can arise in any wave systems with carefully engineered boundary conditions.We then design a metallic waveguide(MWG)array to illustrate that similar FBL can be readily realized and observed with electromagnetic waves.

转角三层石墨烯中的拓扑平带

本文基于连续模型方法系统地计算了转角三层石墨烯(单层+双层)的电子能带结构以及能带的拓扑性质.计算结果表明转角三层石墨烯在魔角(约1.12°)附近存在谷陈数非零的拓扑平带.与转角双层石墨烯不同,小角度的扭转可以在转角三层石墨烯的狄拉克点打开一个小的能隙,通过施加垂直方向的外电场,可以进一步扩大狄拉克点的能隙.因此,转角三层石墨烯中存在的是两条孤立的平带.同时,这两条平带的谷陈数可以通过扭转角度和外加电场来进一步调控.拓扑平带的存在表明转角三层石墨烯是一个研究拓扑能带中关联效应的理想平台.考虑到转角三层石墨烯较低的对称性,作者预期转角三层石墨烯中的关联电子态会显著不同于转角双层石墨烯和转角双两层石墨烯.

USP11通过去泛素化p53调控p53稳定性(英文)

研究目的:深入研究p53的泛素化及稳定性的调控。创新要点:发现一个新的调控p53去泛素化的酶USP11,它可以通过与p53的结合去泛素化并稳定p53,从而揭示了一个新的p53去泛素化调控的机制。研究方法:通过免疫共沉淀发现p53可以与USP11结合(图1a),通过泛素化检测试验发现USP11可以去泛素化p53(图3a和3b),最后通过逆转录-聚合酶链式反应(RT-PCR)试验发现在DNA损伤后,USP11对p53转录活性的提高是非常重要的。重要结论:USP11可通过去泛素化p53来调控p53稳定性。