Two-dimensional(2D)van der Waals materials have attracted tremendous attention due to their versatile physical properties and flexible manipulation approaches.Among the various types of van der Waals materials,α-In_(...Two-dimensional(2D)van der Waals materials have attracted tremendous attention due to their versatile physical properties and flexible manipulation approaches.Among the various types of van der Waals materials,α-In_(2)Se_(3)is remarkable for its intrinsic 2D ferroelectricity and high-performance opto-electronic properties.However,the study of theα-In_(2)Se_(3)system in terahertz(THz)radiation is scarce,although it is promising for electrically controlled THz field manipulation.We investigate theα-In_(2)Se_(3)in different thicknesses and report that the THz generation efficiency induced by femtosecond laser pulses can be largely improved by reducing the thickness from the bulk.Furthermore,we reveal the surge current in thin film coupled with THz emission exhibits a different Auger recombination mode,which is helpful in understanding the mechanism and provides insights into the design of 2D highly efficient THz devices.展开更多
In the past ten years,perovskite solar cells were rapidly developed,but the intrinsic unbalanced charge carrier diffusion lengths within perovskite materials were not fully addressed by either a planar heterojunction ...In the past ten years,perovskite solar cells were rapidly developed,but the intrinsic unbalanced charge carrier diffusion lengths within perovskite materials were not fully addressed by either a planar heterojunction or meso-superstructured perovskite solar cells.In this study,we report bulk heterojunction perovskite solar cells,where perovskite materials CH3NH3PbI3 is blended with solution-processed n-type TiOx nanoparticles as the photoactive layer.Studies indicate that one-step solution-processed CH3NH3PbI3:TiOx bulk-heterojunction thin film possesses enhanced and balanced charge carrier mobilities,superior film morphology with enlarged crystal sizes,and suppressed trapinduced charge recombination.Thus,bulk heterojunction perovskite solar cells by CH3NH3PbI3 mixed with 5 wt% of TiOx,which is processed by one-step method rather than typical two-step method,show a short-circuit current density of 20.93 mA/cm2,an open-circuit voltage of 0.90 V,a fill factor of 80% and with a corresponding power conversion efficiency of 14.91%,which is more than 30% enhancement as compared with that of perovskite solar cells with a planar heterojunction device structure.Moreover,bulk heterojunction perovskite solar cells possess enhanced device stability.All these results demonstrate that perovskite solar cells with a bulk heterojunction device structure are one of apparent approaches to boost device performance.展开更多
基金supported by the National Key R&D Program of China(No.2017YFA0403200)the NSAF(No.U1830206)+1 种基金the Science and Technology Innovation Program of Hunan Province(No.2021RC4026)the National Natural Science Foundation of China(NSFC)(No.62005058)。
文摘Two-dimensional(2D)van der Waals materials have attracted tremendous attention due to their versatile physical properties and flexible manipulation approaches.Among the various types of van der Waals materials,α-In_(2)Se_(3)is remarkable for its intrinsic 2D ferroelectricity and high-performance opto-electronic properties.However,the study of theα-In_(2)Se_(3)system in terahertz(THz)radiation is scarce,although it is promising for electrically controlled THz field manipulation.We investigate theα-In_(2)Se_(3)in different thicknesses and report that the THz generation efficiency induced by femtosecond laser pulses can be largely improved by reducing the thickness from the bulk.Furthermore,we reveal the surge current in thin film coupled with THz emission exhibits a different Auger recombination mode,which is helpful in understanding the mechanism and provides insights into the design of 2D highly efficient THz devices.
基金Air Force Scientific Research Program(No.FA9550-15-1-0292)National Science Foundation(Nos.EECs 1351785 and EECs 1903303)for financial support。
文摘In the past ten years,perovskite solar cells were rapidly developed,but the intrinsic unbalanced charge carrier diffusion lengths within perovskite materials were not fully addressed by either a planar heterojunction or meso-superstructured perovskite solar cells.In this study,we report bulk heterojunction perovskite solar cells,where perovskite materials CH3NH3PbI3 is blended with solution-processed n-type TiOx nanoparticles as the photoactive layer.Studies indicate that one-step solution-processed CH3NH3PbI3:TiOx bulk-heterojunction thin film possesses enhanced and balanced charge carrier mobilities,superior film morphology with enlarged crystal sizes,and suppressed trapinduced charge recombination.Thus,bulk heterojunction perovskite solar cells by CH3NH3PbI3 mixed with 5 wt% of TiOx,which is processed by one-step method rather than typical two-step method,show a short-circuit current density of 20.93 mA/cm2,an open-circuit voltage of 0.90 V,a fill factor of 80% and with a corresponding power conversion efficiency of 14.91%,which is more than 30% enhancement as compared with that of perovskite solar cells with a planar heterojunction device structure.Moreover,bulk heterojunction perovskite solar cells possess enhanced device stability.All these results demonstrate that perovskite solar cells with a bulk heterojunction device structure are one of apparent approaches to boost device performance.
