In this work, ultrathin pure HfO_2 and Al-doped HfO_2films（about 4-nm thick） are prepared by atomic layer deposition and the crystallinities of these films before and after annealing at temperatures ranging from 550...In this work, ultrathin pure HfO_2 and Al-doped HfO_2films（about 4-nm thick） are prepared by atomic layer deposition and the crystallinities of these films before and after annealing at temperatures ranging from 550℃ to 750℃ are analyzed by grazing incidence x-ray diffraction. The as-deposited pure HfO_2 and Al-doped HfO_2 films are both amorphous. After550-℃ annealing, a multiphase consisting of a few orthorhombic, monoclinic and tetragonal phases can be observed in the pure HfO_2 film while the Al-doped HfO_2 film remains amorphous. After annealing at 650℃ and above, a great number of HfO_2 tetragonal phases, a high-temperature phase with higher dielectric constant, can be stabilized in the Al-doped HfO_2 film. As a result, the dielectric constant is enhanced up to about 35. The physical mechanism of the phase transition behavior is discussed from the viewpoint of thermodynamics and kinetics.展开更多
Synergistic optimization of donor-acceptor blend morphologyis a hurdle in the path of realizing efficient non-fullerene small-molecule organic solar cells(NFSMOSCs)due to the anisotropic conjugated backbones of both d...Synergistic optimization of donor-acceptor blend morphologyis a hurdle in the path of realizing efficient non-fullerene small-molecule organic solar cells(NFSMOSCs)due to the anisotropic conjugated backbones of both donor and acceptor.Therefore,developing a facile molecular design strategy to effectively regulate the crystalline properties of photoactive materials,and thus,enable the optimization of blend morphology is of vital importance.In this study,a new donor molecule B1,comprising phenyl-substituted benzodithiophene(BDT)central unit,exhibits strong interaction with the non-fullerene acceptor BO-4 Cl in comparison with its corresponding thiophene-substituted BDT-based material,BTR.As a result,the B1 is affected and induced from an edgeon to a face-on orientation by the acceptor,while the BTR and the acceptor behave individually for the similar molecular orientation in pristine and blend films according to grazing incidence wide angle X-ray scattering results.It means the donor-acceptor blend morphology is synergistically optimized in the B1 system,and the B1:BO-4 Cl-based devices achieve an outstanding power conversion efficiency(PCE)of 15.3%,further certified to be 15.1%by the National Institute of Metrology,China.Our results demonstrate a simple and effective strategy to improve the crystalline properties of the donor molecule as well as synergistically optimize the morphology of the all-small-molecule system,leading to the high-performance NFSM-OSCs.展开更多
Activated carbon(AC)in organic electrolytebased electric double-layer capacitors(EDLCs)usually suffers from low specific capacitance.Most studies on AC focus on improving its surface area and optimizing pore structure...Activated carbon(AC)in organic electrolytebased electric double-layer capacitors(EDLCs)usually suffers from low specific capacitance.Most studies on AC focus on improving its surface area and optimizing pore structures to enhance its electrochemical performance in EDLCs.Unfortunately,the interfacial microenvironment,which is composed of nanoporous carbon and the organic electrolyte confined in it,is always ignored.Herein,a simple and powerful strategy to create AC with an ionophobic surface is proposed to address the poor efficiency of the electric doublelayer process.The polar C±F bonds formed in the AC material are characterized through near-edge X-ray absorption fine structure and X-ray photoelectron spectroscopy.The ionophobic characteristic of YP-F60 s in an organic electrolyte is extensively studied via contact angle measurements and smallangle X-ray scattering spectroscopy.An EDLC constructed with YP-F60 s as the electrode and 1 mol L^(-1) tetraethylammonium tetrafluoroborate/propylene carbonate as the electrolyte demonstrates high specific capacitance,low internal resistance,and excellent cycling stability.Our results successfully demonstrate the importance of the interfacial microenvironment of AC and its confined electrolyte to the electrochemical performance of EDLCs.Our work also offers new perspectives on the use of the CF;plasma technique to fabricate low-cost superior carbon for EDLCs.展开更多
基金Project supported by the National High Technology Research and Development Program of China(Grant No.2015AA016501)the National Natural Science Foundation of China(Grant Nos.61574168 and 61504163)
文摘In this work, ultrathin pure HfO_2 and Al-doped HfO_2films（about 4-nm thick） are prepared by atomic layer deposition and the crystallinities of these films before and after annealing at temperatures ranging from 550℃ to 750℃ are analyzed by grazing incidence x-ray diffraction. The as-deposited pure HfO_2 and Al-doped HfO_2 films are both amorphous. After550-℃ annealing, a multiphase consisting of a few orthorhombic, monoclinic and tetragonal phases can be observed in the pure HfO_2 film while the Al-doped HfO_2 film remains amorphous. After annealing at 650℃ and above, a great number of HfO_2 tetragonal phases, a high-temperature phase with higher dielectric constant, can be stabilized in the Al-doped HfO_2 film. As a result, the dielectric constant is enhanced up to about 35. The physical mechanism of the phase transition behavior is discussed from the viewpoint of thermodynamics and kinetics.
基金financially supported by the Basic and Applied Basic Research Major Program of Guangdong Province(2019B030302007)the National Natural Science Foundation of China(51873217,21734008,51703228,51961135103,51773047 and 51903239)。
文摘Synergistic optimization of donor-acceptor blend morphologyis a hurdle in the path of realizing efficient non-fullerene small-molecule organic solar cells(NFSMOSCs)due to the anisotropic conjugated backbones of both donor and acceptor.Therefore,developing a facile molecular design strategy to effectively regulate the crystalline properties of photoactive materials,and thus,enable the optimization of blend morphology is of vital importance.In this study,a new donor molecule B1,comprising phenyl-substituted benzodithiophene(BDT)central unit,exhibits strong interaction with the non-fullerene acceptor BO-4 Cl in comparison with its corresponding thiophene-substituted BDT-based material,BTR.As a result,the B1 is affected and induced from an edgeon to a face-on orientation by the acceptor,while the BTR and the acceptor behave individually for the similar molecular orientation in pristine and blend films according to grazing incidence wide angle X-ray scattering results.It means the donor-acceptor blend morphology is synergistically optimized in the B1 system,and the B1:BO-4 Cl-based devices achieve an outstanding power conversion efficiency(PCE)of 15.3%,further certified to be 15.1%by the National Institute of Metrology,China.Our results demonstrate a simple and effective strategy to improve the crystalline properties of the donor molecule as well as synergistically optimize the morphology of the all-small-molecule system,leading to the high-performance NFSM-OSCs.
基金supported by the National Natural Science Foundation of China(21203008 and 21975025)Beijing Natural Science Foundation(2172051)the State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,Donghua University。
文摘Activated carbon(AC)in organic electrolytebased electric double-layer capacitors(EDLCs)usually suffers from low specific capacitance.Most studies on AC focus on improving its surface area and optimizing pore structures to enhance its electrochemical performance in EDLCs.Unfortunately,the interfacial microenvironment,which is composed of nanoporous carbon and the organic electrolyte confined in it,is always ignored.Herein,a simple and powerful strategy to create AC with an ionophobic surface is proposed to address the poor efficiency of the electric doublelayer process.The polar C±F bonds formed in the AC material are characterized through near-edge X-ray absorption fine structure and X-ray photoelectron spectroscopy.The ionophobic characteristic of YP-F60 s in an organic electrolyte is extensively studied via contact angle measurements and smallangle X-ray scattering spectroscopy.An EDLC constructed with YP-F60 s as the electrode and 1 mol L^(-1) tetraethylammonium tetrafluoroborate/propylene carbonate as the electrolyte demonstrates high specific capacitance,low internal resistance,and excellent cycling stability.Our results successfully demonstrate the importance of the interfacial microenvironment of AC and its confined electrolyte to the electrochemical performance of EDLCs.Our work also offers new perspectives on the use of the CF;plasma technique to fabricate low-cost superior carbon for EDLCs.
基金financially supported by the National Natural Science Fund for Distinguished Young Scholars(21925506)the National Natural Science Foundation of China(U21A20331 and 81903743)+5 种基金Ningbo S&T Innovation 2025 Major Special Programme(2018B10055)CAS Key Project of Frontier Science Research(QYZDBSSW-SYS030)Ningbo Natural Science Foundation(2021J192)Ningbo Key Scientific and Technological Project(2022Z117)Ningbo Public Welfare Science and Technology Planning Project(2021S149)ZBTI Scientific Research Innovation Team(KYTD202105)。
